Stub with Minitest instead of Mocha

Step 4 in #33162

6 files changed, 699 insertions, 461 deletions

diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index 2ead2c4816..fcb72c2904 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -128,10 +128,10 @@ class FixturesTest < ActiveRecord::TestCase
         ]
       }
 
-      conn.stubs(:max_allowed_packet).returns(packet_size - mysql_margin)
-
-      error = assert_raises(ActiveRecord::ActiveRecordError) { conn.insert_fixtures_set(fixtures) }
-      assert_match(/Fixtures set is too large #{packet_size}\./, error.message)
+      conn.stub(:max_allowed_packet, packet_size - mysql_margin) do
+        error = assert_raises(ActiveRecord::ActiveRecordError) { conn.insert_fixtures_set(fixtures) }
+        assert_match(/Fixtures set is too large #{packet_size}\./, error.message)
+      end
     end
 
     def test_insert_fixture_set_when_max_allowed_packet_is_bigger_than_fixtures_set_size
@@ -143,10 +143,10 @@ class FixturesTest < ActiveRecord::TestCase
         ]
       }
 
-      conn.stubs(:max_allowed_packet).returns(packet_size)
-
-      assert_difference "TrafficLight.count" do
-        conn.insert_fixtures_set(fixtures)
+      conn.stub(:max_allowed_packet, packet_size) do
+        assert_difference "TrafficLight.count" do
+          conn.insert_fixtures_set(fixtures)
+        end
       end
     end
 
@@ -164,12 +164,13 @@ class FixturesTest < ActiveRecord::TestCase
         ]
       }
 
-      conn.stubs(:max_allowed_packet).returns(packet_size)
+      conn.stub(:max_allowed_packet, packet_size) do
+        conn.insert_fixtures_set(fixtures)
 
-      conn.insert_fixtures_set(fixtures)
-      assert_equal 2, subscriber.events.size
-      assert_operator subscriber.events.first.bytesize, :<, packet_size
-      assert_operator subscriber.events.second.bytesize, :<, packet_size
+        assert_equal 2, subscriber.events.size
+        assert_operator subscriber.events.first.bytesize, :<, packet_size
+        assert_operator subscriber.events.second.bytesize, :<, packet_size
+      end
     ensure
       ActiveSupport::Notifications.unsubscribe(subscription)
     end
@@ -188,10 +189,10 @@ class FixturesTest < ActiveRecord::TestCase
         ]
       }
 
-      conn.stubs(:max_allowed_packet).returns(packet_size)
-
-      assert_difference ["TrafficLight.count", "Comment.count"], +1 do
-        conn.insert_fixtures_set(fixtures)
+      conn.stub(:max_allowed_packet, packet_size) do
+        assert_difference ["TrafficLight.count", "Comment.count"], +1 do
+          conn.insert_fixtures_set(fixtures)
+        end
       end
       assert_equal 1, subscriber.events.size
     ensure
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index 15f4cea1a6..75b68b521c 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -297,29 +297,33 @@ class SchemaDumperTest < ActiveRecord::TestCase
     def test_schema_dump_includes_extensions
       connection = ActiveRecord::Base.connection
 
-      connection.stubs(:extensions).returns(["hstore"])
-      output = perform_schema_dump
-      assert_match "# These are extensions that must be enabled", output
-      assert_match %r{enable_extension "hstore"}, output
-
-      connection.stubs(:extensions).returns([])
-      output = perform_schema_dump
-      assert_no_match "# These are extensions that must be enabled", output
-      assert_no_match %r{enable_extension}, output
+      connection.stub(:extensions, ["hstore"]) do
+        output = perform_schema_dump
+        assert_match "# These are extensions that must be enabled", output
+        assert_match %r{enable_extension "hstore"}, output
+      end
+
+      connection.stub(:extensions, []) do
+        output = perform_schema_dump
+        assert_no_match "# These are extensions that must be enabled", output
+        assert_no_match %r{enable_extension}, output
+      end
     end
 
     def test_schema_dump_includes_extensions_in_alphabetic_order
       connection = ActiveRecord::Base.connection
 
-      connection.stubs(:extensions).returns(["hstore", "uuid-ossp", "xml2"])
-      output = perform_schema_dump
-      enabled_extensions = output.scan(%r{enable_extension "(.+)"}).flatten
-      assert_equal ["hstore", "uuid-ossp", "xml2"], enabled_extensions
+      connection.stub(:extensions, ["hstore", "uuid-ossp", "xml2"]) do
+        output = perform_schema_dump
+        enabled_extensions = output.scan(%r{enable_extension "(.+)"}).flatten
+        assert_equal ["hstore", "uuid-ossp", "xml2"], enabled_extensions
+      end
 
-      connection.stubs(:extensions).returns(["uuid-ossp", "xml2", "hstore"])
-      output = perform_schema_dump
-      enabled_extensions = output.scan(%r{enable_extension "(.+)"}).flatten
-      assert_equal ["hstore", "uuid-ossp", "xml2"], enabled_extensions
+      connection.stub(:extensions, ["uuid-ossp", "xml2", "hstore"]) do
+        output = perform_schema_dump
+        enabled_extensions = output.scan(%r{enable_extension "(.+)"}).flatten
+        assert_equal ["hstore", "uuid-ossp", "xml2"], enabled_extensions
+      end
     end
   end
 
diff --git a/activerecord/test/cases/tasks/database_tasks_test.rb b/activerecord/test/cases/tasks/database_tasks_test.rb
index 40b119e54b..80437d4400 100644
--- a/activerecord/test/cases/tasks/database_tasks_test.rb
+++ b/activerecord/test/cases/tasks/database_tasks_test.rb
@@ -17,9 +17,6 @@ module ActiveRecord
           def structure_dump(*); end
         end.new
       )
-      ActiveRecord::Tasks::MySQLDatabaseTasks.stubs(:new).returns @mysql_tasks
-      ActiveRecord::Tasks::PostgreSQLDatabaseTasks.stubs(:new).returns @postgresql_tasks
-      ActiveRecord::Tasks::SQLiteDatabaseTasks.stubs(:new).returns @sqlite_tasks
 
       $stdout, @original_stdout = StringIO.new, $stdout
       $stderr, @original_stderr = StringIO.new, $stderr
@@ -28,6 +25,16 @@ module ActiveRecord
     def teardown
       $stdout, $stderr = @original_stdout, @original_stderr
     end
+
+    def with_stubbed_new
+      ActiveRecord::Tasks::MySQLDatabaseTasks.stub(:new, @mysql_tasks) do
+        ActiveRecord::Tasks::PostgreSQLDatabaseTasks.stub(:new, @postgresql_tasks) do
+          ActiveRecord::Tasks::SQLiteDatabaseTasks.stub(:new, @sqlite_tasks) do
+            yield
+          end
+        end
+      end
+    end
   end
 
   ADAPTERS_TASKS = {
@@ -47,6 +54,7 @@ module ActiveRecord
       ActiveRecord::Tasks::DatabaseTasks.check_protected_environments!
 
       ActiveRecord::Base.protected_environments = [current_env]
+
       assert_raise(ActiveRecord::ProtectedEnvironmentError) do
         ActiveRecord::Tasks::DatabaseTasks.check_protected_environments!
       end
@@ -72,11 +80,12 @@ module ActiveRecord
     end
 
     def test_raises_an_error_if_no_migrations_have_been_made
-      ActiveRecord::InternalMetadata.stubs(:table_exists?).returns(false)
-      ActiveRecord::MigrationContext.any_instance.stubs(:current_version).returns(1)
+      ActiveRecord::InternalMetadata.stub(:table_exists?, false) do
+        ActiveRecord::MigrationContext.any_instance.stubs(:current_version).returns(1)
 
-      assert_raise(ActiveRecord::NoEnvironmentInSchemaError) do
-        ActiveRecord::Tasks::DatabaseTasks.check_protected_environments!
+        assert_raise(ActiveRecord::NoEnvironmentInSchemaError) do
+          ActiveRecord::Tasks::DatabaseTasks.check_protected_environments!
+        end
       end
     end
   end
@@ -89,11 +98,11 @@ module ActiveRecord
       end
       instance = klazz.new
 
-      klazz.stubs(:new).returns instance
-
-      assert_called_with(instance, :structure_dump, ["awesome-file.sql", nil]) do
-        ActiveRecord::Tasks::DatabaseTasks.register_task(/foo/, klazz)
-        ActiveRecord::Tasks::DatabaseTasks.structure_dump({ "adapter" => :foo }, "awesome-file.sql")
+      klazz.stub(:new, instance) do
+        assert_called_with(instance, :structure_dump, ["awesome-file.sql", nil]) do
+          ActiveRecord::Tasks::DatabaseTasks.register_task(/foo/, klazz)
+          ActiveRecord::Tasks::DatabaseTasks.structure_dump({ "adapter" => :foo }, "awesome-file.sql")
+        end
       end
     end
 
@@ -109,8 +118,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_create") do
-        eval("@#{v}").expects(:create)
-        ActiveRecord::Tasks::DatabaseTasks.create "adapter" => k
+        with_stubbed_new do
+          eval("@#{v}").expects(:create)
+          ActiveRecord::Tasks::DatabaseTasks.create "adapter" => k
+        end
       end
     end
   end
@@ -200,70 +211,94 @@ module ActiveRecord
         "test"        => { "database" => "test-db" },
         "production"  => { "url" => "prod-db-url" }
       }
-
-      ActiveRecord::Base.stubs(:configurations).returns(@configurations)
-      ActiveRecord::Base.stubs(:establish_connection)
     end
 
     def test_creates_current_environment_database
-      assert_called_with(
-        ActiveRecord::Tasks::DatabaseTasks,
-        :create,
-        ["database" => "test-db"],
-      ) do
-        ActiveRecord::Tasks::DatabaseTasks.create_current(
-          ActiveSupport::StringInquirer.new("test")
-        )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          ["database" => "test-db"],
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("test")
+          )
+        end
       end
     end
 
     def test_creates_current_environment_database_with_url
-      assert_called_with(
-        ActiveRecord::Tasks::DatabaseTasks,
-        :create,
-        ["url" => "prod-db-url"],
-      ) do
-        ActiveRecord::Tasks::DatabaseTasks.create_current(
-          ActiveSupport::StringInquirer.new("production")
-        )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          ["url" => "prod-db-url"],
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("production")
+          )
+        end
       end
     end
 
     def test_creates_test_and_development_databases_when_env_was_not_specified
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["database" => "dev-db"],
+            ["database" => "test-db"]
+          ],
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     end
 
     def test_creates_test_and_development_databases_when_rails_env_is_development
       old_env = ENV["RAILS_ENV"]
       ENV["RAILS_ENV"] = "development"
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "test-db")
 
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["database" => "dev-db"],
+            ["database" => "test-db"]
+          ],
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     ensure
       ENV["RAILS_ENV"] = old_env
     end
 
     def test_establishes_connection_for_the_given_environments
-      ActiveRecord::Tasks::DatabaseTasks.stubs(:create)
+      ActiveRecord::Tasks::DatabaseTasks.stub(:create, nil) do
+        assert_called_with(ActiveRecord::Base, :establish_connection, [:development]) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
+    end
 
-      ActiveRecord::Base.expects(:establish_connection).with(:development)
+    private
 
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
-    end
+      def with_stubbed_configurations_establish_connection
+        ActiveRecord::Base.stub(:configurations, @configurations) do
+          ActiveRecord::Base.stub(:establish_connection, nil) do
+            yield
+          end
+        end
+      end
   end
 
   class DatabaseTasksCreateCurrentThreeTierTest < ActiveRecord::TestCase
@@ -273,78 +308,104 @@ module ActiveRecord
         "test" => { "primary" => { "database" => "test-db" }, "secondary" => { "database" => "secondary-test-db" } },
         "production" => { "primary" => { "url" => "prod-db-url" }, "secondary" => { "url" => "secondary-prod-db-url" } }
       }
-
-      ActiveRecord::Base.stubs(:configurations).returns(@configurations)
-      ActiveRecord::Base.stubs(:establish_connection)
     end
 
     def test_creates_current_environment_database
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("test")
-      )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("test")
+          )
+        end
+      end
     end
 
     def test_creates_current_environment_database_with_url
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("url" => "prod-db-url")
-
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("url" => "secondary-prod-db-url")
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("production")
-      )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["url" => "prod-db-url"],
+            ["url" => "secondary-prod-db-url"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("production")
+          )
+        end
+      end
     end
 
     def test_creates_test_and_development_databases_when_env_was_not_specified
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "secondary-dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "test-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["database" => "dev-db"],
+            ["database" => "secondary-dev-db"],
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     end
 
     def test_creates_test_and_development_databases_when_rails_env_is_development
       old_env = ENV["RAILS_ENV"]
       ENV["RAILS_ENV"] = "development"
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "secondary-dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "test-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:create).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+
+      with_stubbed_configurations_establish_connection do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :create,
+          [
+            ["database" => "dev-db"],
+            ["database" => "secondary-dev-db"],
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.create_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     ensure
       ENV["RAILS_ENV"] = old_env
     end
 
     def test_establishes_connection_for_the_given_environments_config
-      ActiveRecord::Tasks::DatabaseTasks.stubs(:create)
+      ActiveRecord::Tasks::DatabaseTasks.stub(:create, nil) do
+        ActiveRecord::Base.expects(:establish_connection).with(:development)
 
-      ActiveRecord::Base.expects(:establish_connection).with(:development)
-
-      ActiveRecord::Tasks::DatabaseTasks.create_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+        ActiveRecord::Tasks::DatabaseTasks.create_current(
+          ActiveSupport::StringInquirer.new("development")
+        )
+      end
     end
+
+    private
+
+      def with_stubbed_configurations_establish_connection
+        ActiveRecord::Base.stub(:configurations, @configurations) do
+          ActiveRecord::Base.stub(:establish_connection, nil) do
+            yield
+          end
+        end
+      end
   end
 
   class DatabaseTasksDropTest < ActiveRecord::TestCase
@@ -352,8 +413,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_drop") do
-        eval("@#{v}").expects(:drop)
-        ActiveRecord::Tasks::DatabaseTasks.drop "adapter" => k
+        with_stubbed_new do
+          eval("@#{v}").expects(:drop)
+          ActiveRecord::Tasks::DatabaseTasks.drop "adapter" => k
+        end
       end
     end
   end
@@ -362,8 +425,6 @@ module ActiveRecord
     def setup
       @configurations = { development: { "database" => "my-db" } }
 
-      ActiveRecord::Base.stubs(:configurations).returns(@configurations)
-
       $stdout, @original_stdout = StringIO.new, $stdout
       $stderr, @original_stderr = StringIO.new, $stderr
     end
@@ -375,50 +436,61 @@ module ActiveRecord
     def test_ignores_configurations_without_databases
       @configurations[:development].merge!("database" => nil)
 
-      assert_not_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
-        ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_not_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_all
+        end
       end
     end
 
     def test_ignores_remote_databases
       @configurations[:development].merge!("host" => "my.server.tld")
-      $stderr.stubs(:puts)
 
-      assert_not_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
-        ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_not_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_all
+        end
       end
     end
 
     def test_warning_for_remote_databases
       @configurations[:development].merge!("host" => "my.server.tld")
 
-      ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        ActiveRecord::Tasks::DatabaseTasks.drop_all
 
-      assert_match "This task only modifies local databases. my-db is on a remote host.",
-        $stderr.string
+        assert_match "This task only modifies local databases. my-db is on a remote host.",
+          $stderr.string
+      end
     end
 
     def test_drops_configurations_with_local_ip
       @configurations[:development].merge!("host" => "127.0.0.1")
 
-      assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
-        ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_all
+        end
       end
     end
 
     def test_drops_configurations_with_local_host
       @configurations[:development].merge!("host" => "localhost")
 
-      assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
-        ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_all
+        end
       end
     end
 
     def test_drops_configurations_with_blank_hosts
       @configurations[:development].merge!("host" => nil)
 
-      assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
-        ActiveRecord::Tasks::DatabaseTasks.drop_all
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called(ActiveRecord::Tasks::DatabaseTasks, :drop) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_all
+        end
       end
     end
   end
@@ -430,50 +502,65 @@ module ActiveRecord
         "test"        => { "database" => "test-db" },
         "production"  => { "url" => "prod-db-url" }
       }
-
-      ActiveRecord::Base.stubs(:configurations).returns(@configurations)
     end
 
     def test_drops_current_environment_database
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("test")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(ActiveRecord::Tasks::DatabaseTasks, :drop,
+          ["database" => "test-db"]) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("test")
+          )
+        end
+      end
     end
 
     def test_drops_current_environment_database_with_url
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("url" => "prod-db-url")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("production")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(ActiveRecord::Tasks::DatabaseTasks, :drop,
+          ["url" => "prod-db-url"]) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("production")
+          )
+        end
+      end
     end
 
     def test_drops_test_and_development_databases_when_env_was_not_specified
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["database" => "dev-db"],
+            ["database" => "test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     end
 
     def test_drops_testand_development_databases_when_rails_env_is_development
       old_env = ENV["RAILS_ENV"]
       ENV["RAILS_ENV"] = "development"
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
 
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["database" => "dev-db"],
+            ["database" => "test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     ensure
       ENV["RAILS_ENV"] = old_env
     end
@@ -486,64 +573,81 @@ module ActiveRecord
         "test" => { "primary" => { "database" => "test-db" }, "secondary" => { "database" => "secondary-test-db" } },
         "production" => { "primary" => { "url" => "prod-db-url" }, "secondary" => { "url" => "secondary-prod-db-url" } }
       }
-
-      ActiveRecord::Base.stubs(:configurations).returns(@configurations)
     end
 
     def test_drops_current_environment_database
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("test")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("test")
+          )
+        end
+      end
     end
 
     def test_drops_current_environment_database_with_url
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("url" => "prod-db-url")
-
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("url" => "secondary-prod-db-url")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("production")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["url" => "prod-db-url"],
+            ["url" => "secondary-prod-db-url"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("production")
+          )
+        end
+      end
     end
 
     def test_drops_test_and_development_databases_when_env_was_not_specified
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "secondary-dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["database" => "dev-db"],
+            ["database" => "secondary-dev-db"],
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     end
 
     def test_drops_testand_development_databases_when_rails_env_is_development
       old_env = ENV["RAILS_ENV"]
       ENV["RAILS_ENV"] = "development"
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "secondary-dev-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "test-db")
-      ActiveRecord::Tasks::DatabaseTasks.expects(:drop).
-        with("database" => "secondary-test-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.drop_current(
-        ActiveSupport::StringInquirer.new("development")
-      )
+
+      ActiveRecord::Base.stub(:configurations, @configurations) do
+        assert_called_with(
+          ActiveRecord::Tasks::DatabaseTasks,
+          :drop,
+          [
+            ["database" => "dev-db"],
+            ["database" => "secondary-dev-db"],
+            ["database" => "test-db"],
+            ["database" => "secondary-test-db"]
+          ]
+        ) do
+          ActiveRecord::Tasks::DatabaseTasks.drop_current(
+            ActiveSupport::StringInquirer.new("development")
+          )
+        end
+      end
     ensure
       ENV["RAILS_ENV"] = old_env
     end
@@ -671,10 +775,10 @@ module ActiveRecord
     end
 
     def test_migrate_raise_error_on_failed_check_target_version
-      ActiveRecord::Tasks::DatabaseTasks.stubs(:check_target_version).raises("foo")
-
-      e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
-      assert_equal "foo", e.message
+      ActiveRecord::Tasks::DatabaseTasks.stub(:check_target_version, -> { raise "foo" }) do
+        e = assert_raise(RuntimeError) { ActiveRecord::Tasks::DatabaseTasks.migrate }
+        assert_equal "foo", e.message
+      end
     end
 
     def test_migrate_clears_schema_cache_afterward
@@ -689,8 +793,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_purge") do
-        eval("@#{v}").expects(:purge)
-        ActiveRecord::Tasks::DatabaseTasks.purge "adapter" => k
+        with_stubbed_new do
+          eval("@#{v}").expects(:purge)
+          ActiveRecord::Tasks::DatabaseTasks.purge "adapter" => k
+        end
       end
     end
   end
@@ -702,13 +808,13 @@ module ActiveRecord
         "test"        => { "database" => "test-db" },
         "production"  => { "database" => "prod-db" }
       }
-      ActiveRecord::Base.stubs(:configurations).returns(configurations)
+      ActiveRecord::Base.stub(:configurations, configurations) do
+        ActiveRecord::Tasks::DatabaseTasks.expects(:purge).
+          with("database" => "prod-db")
 
-      ActiveRecord::Tasks::DatabaseTasks.expects(:purge).
-        with("database" => "prod-db")
-
-      assert_called_with(ActiveRecord::Base, :establish_connection, [:production]) do
-        ActiveRecord::Tasks::DatabaseTasks.purge_current("production")
+        assert_called_with(ActiveRecord::Base, :establish_connection, [:production]) do
+          ActiveRecord::Tasks::DatabaseTasks.purge_current("production")
+        end
       end
     end
   end
@@ -716,12 +822,12 @@ module ActiveRecord
   class DatabaseTasksPurgeAllTest < ActiveRecord::TestCase
     def test_purge_all_local_configurations
       configurations = { development: { "database" => "my-db" } }
-      ActiveRecord::Base.stubs(:configurations).returns(configurations)
+      ActiveRecord::Base.stub(:configurations, configurations) do
+        ActiveRecord::Tasks::DatabaseTasks.expects(:purge).
+          with("database" => "my-db")
 
-      ActiveRecord::Tasks::DatabaseTasks.expects(:purge).
-        with("database" => "my-db")
-
-      ActiveRecord::Tasks::DatabaseTasks.purge_all
+        ActiveRecord::Tasks::DatabaseTasks.purge_all
+      end
     end
   end
 
@@ -730,8 +836,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_charset") do
-        eval("@#{v}").expects(:charset)
-        ActiveRecord::Tasks::DatabaseTasks.charset "adapter" => k
+        with_stubbed_new do
+          eval("@#{v}").expects(:charset)
+          ActiveRecord::Tasks::DatabaseTasks.charset "adapter" => k
+        end
       end
     end
   end
@@ -741,8 +849,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_collation") do
-        eval("@#{v}").expects(:collation)
-        ActiveRecord::Tasks::DatabaseTasks.collation "adapter" => k
+        with_stubbed_new do
+          eval("@#{v}").expects(:collation)
+          ActiveRecord::Tasks::DatabaseTasks.collation "adapter" => k
+        end
       end
     end
   end
@@ -854,8 +964,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_structure_dump") do
-        eval("@#{v}").expects(:structure_dump).with("awesome-file.sql", nil)
-        ActiveRecord::Tasks::DatabaseTasks.structure_dump({ "adapter" => k }, "awesome-file.sql")
+        with_stubbed_new do
+          eval("@#{v}").expects(:structure_dump).with("awesome-file.sql", nil)
+          ActiveRecord::Tasks::DatabaseTasks.structure_dump({ "adapter" => k }, "awesome-file.sql")
+        end
       end
     end
   end
@@ -865,8 +977,10 @@ module ActiveRecord
 
     ADAPTERS_TASKS.each do |k, v|
       define_method("test_#{k}_structure_load") do
-        eval("@#{v}").expects(:structure_load).with("awesome-file.sql", nil)
-        ActiveRecord::Tasks::DatabaseTasks.structure_load({ "adapter" => k }, "awesome-file.sql")
+        with_stubbed_new do
+          eval("@#{v}").expects(:structure_load).with("awesome-file.sql", nil)
+          ActiveRecord::Tasks::DatabaseTasks.structure_load({ "adapter" => k }, "awesome-file.sql")
+        end
       end
     end
   end
@@ -881,16 +995,18 @@ module ActiveRecord
 
   class DatabaseTasksCheckSchemaFileDefaultsTest < ActiveRecord::TestCase
     def test_check_schema_file_defaults
-      ActiveRecord::Tasks::DatabaseTasks.stubs(:db_dir).returns("/tmp")
-      assert_equal "/tmp/schema.rb", ActiveRecord::Tasks::DatabaseTasks.schema_file
+      ActiveRecord::Tasks::DatabaseTasks.stub(:db_dir, "/tmp") do
+        assert_equal "/tmp/schema.rb", ActiveRecord::Tasks::DatabaseTasks.schema_file
+      end
     end
   end
 
   class DatabaseTasksCheckSchemaFileSpecifiedFormatsTest < ActiveRecord::TestCase
     { ruby: "schema.rb", sql: "structure.sql" }.each_pair do |fmt, filename|
       define_method("test_check_schema_file_for_#{fmt}_format") do
-        ActiveRecord::Tasks::DatabaseTasks.stubs(:db_dir).returns("/tmp")
-        assert_equal "/tmp/#{filename}", ActiveRecord::Tasks::DatabaseTasks.schema_file(fmt)
+        ActiveRecord::Tasks::DatabaseTasks.stub(:db_dir, "/tmp") do
+          assert_equal "/tmp/#{filename}", ActiveRecord::Tasks::DatabaseTasks.schema_file(fmt)
+        end
       end
     end
   end
diff --git a/activerecord/test/cases/tasks/mysql_rake_test.rb b/activerecord/test/cases/tasks/mysql_rake_test.rb
index 155b060b1e..6ed9fdb7fa 100644
--- a/activerecord/test/cases/tasks/mysql_rake_test.rb
+++ b/activerecord/test/cases/tasks/mysql_rake_test.rb
@@ -12,10 +12,6 @@ if current_adapter?(:Mysql2Adapter)
           "adapter"  => "mysql2",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -25,54 +21,81 @@ if current_adapter?(:Mysql2Adapter)
       end
 
       def test_establishes_connection_without_database
-        ActiveRecord::Base.expects(:establish_connection).
-          with("adapter" => "mysql2", "database" => nil)
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        ActiveRecord::Base.stubs(:establish_connection)
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.expects(:establish_connection).
+            with("adapter" => "mysql2", "database" => nil)
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_creates_database_with_no_default_options
-        @connection.expects(:create_database).
-          with("my-app-db", {})
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", {})
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_creates_database_with_given_encoding
-        @connection.expects(:create_database).
-          with("my-app-db", charset: "latin1")
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", charset: "latin1")
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge("encoding" => "latin1")
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge("encoding" => "latin1")
+        end
       end
 
       def test_creates_database_with_given_collation
-        @connection.expects(:create_database).
-          with("my-app-db", collation: "latin1_swedish_ci")
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", collation: "latin1_swedish_ci")
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge("collation" => "latin1_swedish_ci")
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge("collation" => "latin1_swedish_ci")
+        end
       end
 
       def test_establishes_connection_to_database
-        ActiveRecord::Base.expects(:establish_connection).with(@configuration)
+        ActiveRecord::Base.stubs(:establish_connection)
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.expects(:establish_connection).with(@configuration)
+
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_when_database_created_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
 
-        assert_equal "Created database 'my-app-db'\n", $stdout.string
+          assert_equal "Created database 'my-app-db'\n", $stdout.string
+        end
       end
 
       def test_create_when_database_exists_outputs_info_to_stderr
-        ActiveRecord::Base.connection.stubs(:create_database).raises(
-          ActiveRecord::Tasks::DatabaseAlreadyExists
-        )
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Base.connection.stub(
+            :create_database,
+            proc { raise ActiveRecord::Tasks::DatabaseAlreadyExists }
+          ) do
+            ActiveRecord::Tasks::DatabaseTasks.create @configuration
+
+            assert_equal "Database 'my-app-db' already exists\n", $stderr.string
+          end
+        end
+      end
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+      private
 
-        assert_equal "Database 'my-app-db' already exists\n", $stderr.string
-      end
+        def with_stubbed_connection_establish_connection
+          ActiveRecord::Base.stub(:establish_connection, true) do
+            ActiveRecord::Base.stub(:connection, @connection) do
+              yield
+            end
+          end
+        end
     end
 
     class MysqlDBCreateWithInvalidPermissionsTest < ActiveRecord::TestCase
@@ -84,9 +107,6 @@ if current_adapter?(:Mysql2Adapter)
           "username" => "pat",
           "password" => "wossname"
         }
-
-        ActiveRecord::Base.stubs(:establish_connection).raises(@error)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -96,8 +116,12 @@ if current_adapter?(:Mysql2Adapter)
       end
 
       def test_raises_error
-        assert_raises(Mysql2::Error, "Invalid permissions") do
-          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.stub(:establish_connection, -> * { raise @error }) do
+            assert_raises(Mysql2::Error, "Invalid permissions") do
+              ActiveRecord::Tasks::DatabaseTasks.create @configuration
+            end
+          end
         end
       end
     end
@@ -109,10 +133,6 @@ if current_adapter?(:Mysql2Adapter)
           "adapter"  => "mysql2",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -122,22 +142,38 @@ if current_adapter?(:Mysql2Adapter)
       end
 
       def test_establishes_connection_to_mysql_database
-        ActiveRecord::Base.expects(:establish_connection).with @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Base.expects(:establish_connection).with @configuration
 
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        end
       end
 
       def test_drops_database
-        @connection.expects(:drop_database).with("my-app-db")
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:drop_database).with("my-app-db")
 
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        end
       end
 
       def test_when_database_dropped_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
 
-        assert_equal "Dropped database 'my-app-db'\n", $stdout.string
+          assert_equal "Dropped database 'my-app-db'\n", $stdout.string
+        end
       end
+
+      private
+
+        def with_stubbed_connection_establish_connection
+          ActiveRecord::Base.stub(:establish_connection, true) do
+            ActiveRecord::Base.stub(:connection, @connection) do
+              yield
+            end
+          end
+        end
     end
 
     class MySQLPurgeTest < ActiveRecord::TestCase
@@ -147,31 +183,44 @@ if current_adapter?(:Mysql2Adapter)
           "adapter"  => "mysql2",
           "database" => "test-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
       end
 
       def test_establishes_connection_to_the_appropriate_database
-        ActiveRecord::Base.expects(:establish_connection).with(@configuration)
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Base.expects(:establish_connection).with(@configuration)
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+        end
       end
 
       def test_recreates_database_with_no_default_options
-        @connection.expects(:recreate_database).
-          with("test-db", {})
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:recreate_database).
+            with("test-db", {})
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+        end
       end
 
       def test_recreates_database_with_the_given_options
-        @connection.expects(:recreate_database).
-          with("test-db", charset: "latin", collation: "latin1_swedish_ci")
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:recreate_database).
+            with("test-db", charset: "latin", collation: "latin1_swedish_ci")
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration.merge(
-          "encoding" => "latin", "collation" => "latin1_swedish_ci")
+          ActiveRecord::Tasks::DatabaseTasks.purge @configuration.merge(
+            "encoding" => "latin", "collation" => "latin1_swedish_ci")
+        end
       end
+
+      private
+
+        def with_stubbed_connection_establish_connection
+          ActiveRecord::Base.stub(:establish_connection, true) do
+            ActiveRecord::Base.stub(:connection, @connection) do
+              yield
+            end
+          end
+        end
     end
 
     class MysqlDBCharsetTest < ActiveRecord::TestCase
@@ -181,13 +230,13 @@ if current_adapter?(:Mysql2Adapter)
           "adapter"  => "mysql2",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
       end
 
       def test_db_retrieves_charset
-        @connection.expects(:charset)
-        ActiveRecord::Tasks::DatabaseTasks.charset @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          @connection.expects(:charset)
+          ActiveRecord::Tasks::DatabaseTasks.charset @configuration
+        end
       end
     end
 
@@ -198,13 +247,13 @@ if current_adapter?(:Mysql2Adapter)
           "adapter"  => "mysql2",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
       end
 
       def test_db_retrieves_collation
-        @connection.expects(:collation)
-        ActiveRecord::Tasks::DatabaseTasks.collation @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          @connection.expects(:collation)
+          ActiveRecord::Tasks::DatabaseTasks.collation @configuration
+        end
       end
     end
 
@@ -241,15 +290,15 @@ if current_adapter?(:Mysql2Adapter)
 
       def test_structure_dump_with_ignore_tables
         filename = "awesome-file.sql"
-        ActiveRecord::SchemaDumper.expects(:ignore_tables).returns(["foo", "bar"])
-
-        assert_called_with(
-          Kernel,
-          :system,
-          ["mysqldump", "--result-file", filename, "--no-data", "--routines", "--skip-comments", "--ignore-table=test-db.foo", "--ignore-table=test-db.bar", "test-db"],
-          returns: true
-        ) do
-          ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
+        ActiveRecord::SchemaDumper.stub(:ignore_tables, ["foo", "bar"]) do
+          assert_called_with(
+            Kernel,
+            :system,
+            ["mysqldump", "--result-file", filename, "--no-data", "--routines", "--skip-comments", "--ignore-table=test-db.foo", "--ignore-table=test-db.bar", "test-db"],
+            returns: true
+          ) do
+            ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, filename)
+          end
         end
       end
 
diff --git a/activerecord/test/cases/tasks/postgresql_rake_test.rb b/activerecord/test/cases/tasks/postgresql_rake_test.rb
index 728a13f2e6..1dcb06ceff 100644
--- a/activerecord/test/cases/tasks/postgresql_rake_test.rb
+++ b/activerecord/test/cases/tasks/postgresql_rake_test.rb
@@ -12,10 +12,6 @@ if current_adapter?(:PostgreSQLAdapter)
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -25,66 +21,94 @@ if current_adapter?(:PostgreSQLAdapter)
       end
 
       def test_establishes_connection_to_postgresql_database
-        ActiveRecord::Base.expects(:establish_connection).with(
-          "adapter"            => "postgresql",
-          "database"           => "postgres",
-          "schema_search_path" => "public"
-        )
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        ActiveRecord::Base.stubs(:establish_connection)
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.expects(:establish_connection).with(
+            "adapter"            => "postgresql",
+            "database"           => "postgres",
+            "schema_search_path" => "public"
+          )
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_creates_database_with_default_encoding
-        @connection.expects(:create_database).
-          with("my-app-db", @configuration.merge("encoding" => "utf8"))
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", @configuration.merge("encoding" => "utf8"))
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_creates_database_with_given_encoding
-        @connection.expects(:create_database).
-          with("my-app-db", @configuration.merge("encoding" => "latin"))
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", @configuration.merge("encoding" => "latin"))
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration.
-          merge("encoding" => "latin")
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration.
+            merge("encoding" => "latin")
+        end
       end
 
       def test_creates_database_with_given_collation_and_ctype
-        @connection.expects(:create_database).
-          with("my-app-db", @configuration.merge("encoding" => "utf8", "collation" => "ja_JP.UTF8", "ctype" => "ja_JP.UTF8"))
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:create_database).
+            with("my-app-db", @configuration.merge("encoding" => "utf8", "collation" => "ja_JP.UTF8", "ctype" => "ja_JP.UTF8"))
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration.
-          merge("collation" => "ja_JP.UTF8", "ctype" => "ja_JP.UTF8")
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration.
+            merge("collation" => "ja_JP.UTF8", "ctype" => "ja_JP.UTF8")
+        end
       end
 
       def test_establishes_connection_to_new_database
-        ActiveRecord::Base.expects(:establish_connection).with(@configuration)
+        ActiveRecord::Base.stubs(:establish_connection)
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.expects(:establish_connection).with(@configuration)
 
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        end
       end
 
       def test_db_create_with_error_prints_message
-        ActiveRecord::Base.stubs(:establish_connection).raises(Exception)
-
-        assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration }
-        assert_match "Couldn't create database for #{@configuration.inspect}", $stderr.string
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.stub(:establish_connection, -> * { raise Exception }) do
+            assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration }
+            assert_match "Couldn't create database for #{@configuration.inspect}", $stderr.string
+          end
+        end
       end
 
       def test_when_database_created_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration
 
-        assert_equal "Created database 'my-app-db'\n", $stdout.string
+          assert_equal "Created database 'my-app-db'\n", $stdout.string
+        end
       end
 
       def test_create_when_database_exists_outputs_info_to_stderr
-        ActiveRecord::Base.connection.stubs(:create_database).raises(
-          ActiveRecord::Tasks::DatabaseAlreadyExists
-        )
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Base.connection.stub(
+            :create_database,
+            proc { raise ActiveRecord::Tasks::DatabaseAlreadyExists }
+          ) do
+            ActiveRecord::Tasks::DatabaseTasks.create @configuration
 
-        assert_equal "Database 'my-app-db' already exists\n", $stderr.string
+            assert_equal "Database 'my-app-db' already exists\n", $stderr.string
+          end
+        end
       end
+
+      private
+
+        def with_stubbed_connection_establish_connection
+          ActiveRecord::Base.stub(:connection, @connection) do
+            ActiveRecord::Base.stub(:establish_connection, nil) do
+              yield
+            end
+          end
+        end
     end
 
     class PostgreSQLDBDropTest < ActiveRecord::TestCase
@@ -94,10 +118,6 @@ if current_adapter?(:PostgreSQLAdapter)
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -107,26 +127,41 @@ if current_adapter?(:PostgreSQLAdapter)
       end
 
       def test_establishes_connection_to_postgresql_database
-        ActiveRecord::Base.expects(:establish_connection).with(
-          "adapter"            => "postgresql",
-          "database"           => "postgres",
-          "schema_search_path" => "public"
-        )
-
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          ActiveRecord::Base.expects(:establish_connection).with(
+            "adapter"            => "postgresql",
+            "database"           => "postgres",
+            "schema_search_path" => "public"
+          )
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        end
       end
 
       def test_drops_database
-        @connection.expects(:drop_database).with("my-app-db")
+        with_stubbed_connection_establish_connection do
+          @connection.expects(:drop_database).with("my-app-db")
 
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        end
       end
 
       def test_when_database_dropped_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration
+        with_stubbed_connection_establish_connection do
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration
 
-        assert_equal "Dropped database 'my-app-db'\n", $stdout.string
+          assert_equal "Dropped database 'my-app-db'\n", $stdout.string
+        end
       end
+
+      private
+
+        def with_stubbed_connection_establish_connection
+          ActiveRecord::Base.stub(:connection, @connection) do
+            ActiveRecord::Base.stub(:establish_connection, nil) do
+              yield
+            end
+          end
+        end
     end
 
     class PostgreSQLPurgeTest < ActiveRecord::TestCase
@@ -139,45 +174,68 @@ if current_adapter?(:PostgreSQLAdapter)
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
       end
 
       def test_clears_active_connections
-        ActiveRecord::Base.expects(:clear_active_connections!)
+        with_stubbed_connection do
+          ActiveRecord::Base.stub(:establish_connection, nil) do
+            ActiveRecord::Base.expects(:clear_active_connections!)
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+            ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          end
+        end
       end
 
       def test_establishes_connection_to_postgresql_database
-        ActiveRecord::Base.expects(:establish_connection).with(
-          "adapter"            => "postgresql",
-          "database"           => "postgres",
-          "schema_search_path" => "public"
-        )
-
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+        ActiveRecord::Base.stubs(:establish_connection)
+        with_stubbed_connection do
+          ActiveRecord::Base.expects(:establish_connection).with(
+            "adapter"            => "postgresql",
+            "database"           => "postgres",
+            "schema_search_path" => "public"
+          )
+
+          ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+        end
       end
 
       def test_drops_database
-        @connection.expects(:drop_database).with("my-app-db")
+        with_stubbed_connection do
+          ActiveRecord::Base.stub(:establish_connection, nil) do
+            @connection.expects(:drop_database).with("my-app-db")
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+            ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          end
+        end
       end
 
       def test_creates_database
-        @connection.expects(:create_database).
-          with("my-app-db", @configuration.merge("encoding" => "utf8"))
+        with_stubbed_connection do
+          ActiveRecord::Base.stub(:establish_connection, true) do
+            @connection.expects(:create_database).
+              with("my-app-db", @configuration.merge("encoding" => "utf8"))
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+            ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          end
+        end
       end
 
       def test_establishes_connection
-        ActiveRecord::Base.expects(:establish_connection).with(@configuration)
+        ActiveRecord::Base.stubs(:establish_connection)
+        with_stubbed_connection do
+          ActiveRecord::Base.expects(:establish_connection).with(@configuration)
 
-        ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+          ActiveRecord::Tasks::DatabaseTasks.purge @configuration
+        end
       end
+
+      private
+
+        def with_stubbed_connection
+          ActiveRecord::Base.stub(:connection, @connection) do
+            yield
+          end
+        end
     end
 
     class PostgreSQLDBCharsetTest < ActiveRecord::TestCase
@@ -187,14 +245,14 @@ if current_adapter?(:PostgreSQLAdapter)
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
-        ActiveRecord::Base.stubs(:establish_connection)
       end
 
       def test_db_retrieves_charset
-        @connection.expects(:encoding)
-        ActiveRecord::Tasks::DatabaseTasks.charset @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          @connection.expects(:encoding)
+
+          ActiveRecord::Tasks::DatabaseTasks.charset @configuration
+        end
       end
     end
 
@@ -205,13 +263,14 @@ if current_adapter?(:PostgreSQLAdapter)
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
       end
 
       def test_db_retrieves_collation
-        @connection.expects(:collation)
-        ActiveRecord::Tasks::DatabaseTasks.collation @configuration
+        ActiveRecord::Base.stub(:connection, @connection) do
+          @connection.expects(:collation)
+
+          ActiveRecord::Tasks::DatabaseTasks.collation @configuration
+        end
       end
     end
 
@@ -241,12 +300,12 @@ if current_adapter?(:PostgreSQLAdapter)
       end
 
       def test_structure_dump_header_comments_removed
-        Kernel.stubs(:system).returns(true)
-        File.write(@filename, "-- header comment\n\n-- more header comment\n statement \n-- lower comment\n")
-
-        ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+        Kernel.stub(:system, true) do
+          File.write(@filename, "-- header comment\n\n-- more header comment\n statement \n-- lower comment\n")
+          ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
 
-        assert_equal [" statement \n", "-- lower comment\n"], File.readlines(@filename).first(2)
+          assert_equal [" statement \n", "-- lower comment\n"], File.readlines(@filename).first(2)
+        end
       end
 
       def test_structure_dump_with_extra_flags
diff --git a/activerecord/test/cases/tasks/sqlite_rake_test.rb b/activerecord/test/cases/tasks/sqlite_rake_test.rb
index ce630f794e..2fe7f54b17 100644
--- a/activerecord/test/cases/tasks/sqlite_rake_test.rb
+++ b/activerecord/test/cases/tasks/sqlite_rake_test.rb
@@ -13,9 +13,6 @@ if current_adapter?(:SQLite3Adapter)
           "adapter"  => "sqlite3",
           "database" => @database
         }
-
-        ActiveRecord::Base.stubs(:establish_connection)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -25,44 +22,50 @@ if current_adapter?(:SQLite3Adapter)
       end
 
       def test_db_checks_database_exists
-        File.expects(:exist?).with(@database).returns(false)
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+        ActiveRecord::Base.stub(:establish_connection, true) do
+          assert_called_with(File, :exist?, [@database], returns: false) do
+            ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+          end
+        end
       end
 
       def test_when_db_created_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+        ActiveRecord::Base.stub(:establish_connection, true) do
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
 
-        assert_equal "Created database '#{@database}'\n", $stdout.string
+          assert_equal "Created database '#{@database}'\n", $stdout.string
+        end
       end
 
       def test_db_create_when_file_exists
-        File.stubs(:exist?).returns(true)
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+        File.stub(:exist?, true) do
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
 
-        assert_equal "Database '#{@database}' already exists\n", $stderr.string
+          assert_equal "Database '#{@database}' already exists\n", $stderr.string
+        end
       end
 
       def test_db_create_with_file_does_nothing
-        File.stubs(:exist?).returns(true)
+        File.stub(:exist?, true) do
+          ActiveRecord::Base.expects(:establish_connection).never
 
-        ActiveRecord::Base.expects(:establish_connection).never
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+          ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+        end
       end
 
       def test_db_create_establishes_a_connection
-        ActiveRecord::Base.expects(:establish_connection).with(@configuration)
-
-        ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+        File.stub(:exist?, false) do
+          assert_called_with(ActiveRecord::Base, :establish_connection, [@configuration]) do
+            ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root"
+          end
+        end
       end
 
       def test_db_create_with_error_prints_message
-        ActiveRecord::Base.stubs(:establish_connection).raises(Exception)
-
-        assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root" }
-        assert_match "Couldn't create database for #{@configuration.inspect}", $stderr.string
+        ActiveRecord::Base.stub(:establish_connection, proc { raise Exception }) do
+          assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration, "/rails/root" }
+          assert_match "Couldn't create database for #{@configuration.inspect}", $stderr.string
+        end
       end
     end
 
@@ -78,10 +81,6 @@ if current_adapter?(:SQLite3Adapter)
           def absolute?; true end
         end.new
 
-        Pathname.stubs(:new).returns(@path)
-        File.stubs(:join).returns("/former/relative/path")
-        FileUtils.stubs(:rm)
-
         $stdout, @original_stdout = StringIO.new, $stdout
         $stderr, @original_stderr = StringIO.new, $stderr
       end
@@ -97,32 +96,41 @@ if current_adapter?(:SQLite3Adapter)
       end
 
       def test_removes_file_with_absolute_path
-        FileUtils.expects(:rm).with("/absolute/path")
-
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+        Pathname.stub(:new, @path) do
+          assert_called_with(FileUtils, :rm, ["/absolute/path"]) do
+            ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+          end
+        end
       end
 
       def test_generates_absolute_path_with_given_root
-        @path.stubs(:absolute?)
-
-        File.expects(:join).with("/rails/root", @path).
-          returns("/former/relative/path")
-
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+        Pathname.stub(:new, @path) do
+          @path.stub(:absolute?, false) do
+            assert_called_with(File, :join, ["/rails/root", @path],
+              returns: "/former/relative/path"
+            ) do
+              ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+            end
+          end
+        end
       end
 
       def test_removes_file_with_relative_path
-        @path.stubs(:absolute?)
-
-        FileUtils.expects(:rm).with("/former/relative/path")
-
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+        File.stub(:join, "/former/relative/path") do
+          @path.stub(:absolute?, false) do
+            assert_called_with(FileUtils, :rm, ["/former/relative/path"]) do
+              ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+            end
+          end
+        end
       end
 
       def test_when_db_dropped_successfully_outputs_info_to_stdout
-        ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
+        FileUtils.stub(:rm, nil) do
+          ActiveRecord::Tasks::DatabaseTasks.drop @configuration, "/rails/root"
 
-        assert_equal "Dropped database '#{@database}'\n", $stdout.string
+          assert_equal "Dropped database '#{@database}'\n", $stdout.string
+        end
       end
     end
 
@@ -134,13 +142,14 @@ if current_adapter?(:SQLite3Adapter)
           "adapter"  => "sqlite3",
           "database" => @database
         }
-
-        ActiveRecord::Base.stubs(:connection).returns(@connection)
       end
 
       def test_db_retrieves_charset
-        @connection.expects(:encoding)
-        ActiveRecord::Tasks::DatabaseTasks.charset @configuration, "/rails/root"
+        ActiveRecord::Base.stub(:connection, @connection) do
+          assert_called(@connection, :encoding) do
+            ActiveRecord::Tasks::DatabaseTasks.charset @configuration, "/rails/root"
+          end
+        end
       end
     end