1 files changed, 158 insertions, 22 deletions

diff --git a/activesupport/test/test_case_test.rb b/activesupport/test/test_case_test.rb
index 18228a2ac5..79b75a001a 100644
--- a/activesupport/test/test_case_test.rb
+++ b/activesupport/test/test_case_test.rb
@@ -1,4 +1,6 @@
-require 'abstract_unit'
+# frozen_string_literal: true
+
+require "abstract_unit"
 
 class AssertDifferenceTest < ActiveSupport::TestCase
   def setup
@@ -20,21 +22,21 @@ class AssertDifferenceTest < ActiveSupport::TestCase
     assert_equal true, assert_not(false)
 
     e = assert_raises(Minitest::Assertion) { assert_not true }
-    assert_equal 'Expected true to be nil or false', e.message
+    assert_equal "Expected true to be nil or false", e.message
 
-    e = assert_raises(Minitest::Assertion) { assert_not true, 'custom' }
-    assert_equal 'custom', e.message
+    e = assert_raises(Minitest::Assertion) { assert_not true, "custom" }
+    assert_equal "custom", e.message
   end
 
   def test_assert_no_difference_pass
-    assert_no_difference '@object.num' do
+    assert_no_difference "@object.num" do
       # ...
     end
   end
 
   def test_assert_no_difference_fail
     error = assert_raises(Minitest::Assertion) do
-      assert_no_difference '@object.num' do
+      assert_no_difference "@object.num" do
         @object.increment
       end
     end
@@ -43,7 +45,7 @@ class AssertDifferenceTest < ActiveSupport::TestCase
 
   def test_assert_no_difference_with_message_fail
     error = assert_raises(Minitest::Assertion) do
-      assert_no_difference '@object.num', 'Object Changed' do
+      assert_no_difference "@object.num", "Object Changed" do
         @object.increment
       end
     end
@@ -51,13 +53,13 @@ class AssertDifferenceTest < ActiveSupport::TestCase
   end
 
   def test_assert_difference
-    assert_difference '@object.num', +1 do
+    assert_difference "@object.num", +1 do
       @object.increment
     end
   end
 
   def test_assert_difference_retval
-    incremented = assert_difference '@object.num', +1 do
+    incremented = assert_difference "@object.num", +1 do
       @object.increment
     end
 
@@ -65,40 +67,41 @@ class AssertDifferenceTest < ActiveSupport::TestCase
   end
 
   def test_assert_difference_with_implicit_difference
-    assert_difference '@object.num' do
+    assert_difference "@object.num" do
       @object.increment
     end
   end
 
   def test_arbitrary_expression
-    assert_difference '@object.num + 1', +2 do
+    assert_difference "@object.num + 1", +2 do
       @object.increment
       @object.increment
     end
   end
 
   def test_negative_differences
-    assert_difference '@object.num', -1 do
+    assert_difference "@object.num", -1 do
       @object.decrement
     end
   end
 
   def test_expression_is_evaluated_in_the_appropriate_scope
     silence_warnings do
-      local_scope = local_scope = 'foo'
-      assert_difference('local_scope; @object.num') { @object.increment }
+      local_scope = "foo"
+      local_scope = local_scope  # to suppress unused variable warning
+      assert_difference("local_scope; @object.num") { @object.increment }
     end
   end
 
   def test_array_of_expressions
-    assert_difference [ '@object.num', '@object.num + 1' ], +1 do
+    assert_difference [ "@object.num", "@object.num + 1" ], +1 do
       @object.increment
     end
   end
 
   def test_array_of_expressions_identify_failure
     assert_raises(Minitest::Assertion) do
-      assert_difference ['@object.num', '1 + 1'] do
+      assert_difference ["@object.num", "1 + 1"] do
         @object.increment
       end
     end
@@ -106,14 +109,147 @@ class AssertDifferenceTest < ActiveSupport::TestCase
 
   def test_array_of_expressions_identify_failure_when_message_provided
     assert_raises(Minitest::Assertion) do
-      assert_difference ['@object.num', '1 + 1'], 1, 'something went wrong' do
+      assert_difference ["@object.num", "1 + 1"], 1, "something went wrong" do
+        @object.increment
+      end
+    end
+  end
+
+  def test_assert_changes_pass
+    assert_changes "@object.num" do
+      @object.increment
+    end
+  end
+
+  def test_assert_changes_pass_with_lambda
+    assert_changes -> { @object.num } do
+      @object.increment
+    end
+  end
+
+  def test_assert_changes_with_from_option
+    assert_changes "@object.num", from: 0 do
+      @object.increment
+    end
+  end
+
+  def test_assert_changes_with_from_option_with_wrong_value
+    assert_raises Minitest::Assertion do
+      assert_changes "@object.num", from: -1 do
+        @object.increment
+      end
+    end
+  end
+
+  def test_assert_changes_with_from_option_with_nil
+    error = assert_raises Minitest::Assertion do
+      assert_changes "@object.num", from: nil do
+        @object.increment
+      end
+    end
+    assert_equal "\"@object.num\" isn't nil", error.message
+  end
+
+  def test_assert_changes_with_to_option
+    assert_changes "@object.num", to: 1 do
+      @object.increment
+    end
+  end
+
+  def test_assert_changes_with_to_option_but_no_change_has_special_message
+    error = assert_raises Minitest::Assertion do
+      assert_changes "@object.num", to: 0 do
+        # no changes
+      end
+    end
+
+    assert_equal "\"@object.num\" didn't change. It was already 0", error.message
+  end
+
+  def test_assert_changes_with_wrong_to_option
+    assert_raises Minitest::Assertion do
+      assert_changes "@object.num", to: 2 do
         @object.increment
       end
     end
   end
-end
 
-class AlsoDoingNothingTest < ActiveSupport::TestCase
+  def test_assert_changes_with_from_option_and_to_option
+    assert_changes "@object.num", from: 0, to: 1 do
+      @object.increment
+    end
+  end
+
+  def test_assert_changes_with_from_and_to_options_and_wrong_to_value
+    assert_raises Minitest::Assertion do
+      assert_changes "@object.num", from: 0, to: 2 do
+        @object.increment
+      end
+    end
+  end
+
+  def test_assert_changes_works_with_any_object
+    # Silences: instance variable @new_object not initialized.
+    retval = silence_warnings do
+      assert_changes :@new_object, from: nil, to: 42 do
+        @new_object = 42
+      end
+    end
+
+    assert_equal 42, retval
+  end
+
+  def test_assert_changes_works_with_nil
+    oldval = @object
+
+    retval = assert_changes :@object, from: oldval, to: nil do
+      @object = nil
+    end
+
+    assert_nil retval
+  end
+
+  def test_assert_changes_with_to_and_case_operator
+    token = nil
+
+    assert_changes -> { token }, to: /\w{32}/ do
+      token = SecureRandom.hex
+    end
+  end
+
+  def test_assert_changes_with_to_and_from_and_case_operator
+    token = SecureRandom.hex
+
+    assert_changes -> { token }, from: /\w{32}/, to: /\w{32}/ do
+      token = SecureRandom.hex
+    end
+  end
+
+  def test_assert_changes_with_message
+    error = assert_raises Minitest::Assertion do
+      assert_changes "@object.num", "@object.num should 1", to: 1 do
+        @object.decrement
+      end
+    end
+
+    assert_equal "@object.num should 1.\n\"@object.num\" didn't change to 1", error.message
+  end
+
+  def test_assert_no_changes_pass
+    assert_no_changes "@object.num" do
+      # ...
+    end
+  end
+
+  def test_assert_no_changes_with_message
+    error = assert_raises Minitest::Assertion do
+      assert_no_changes "@object.num", "@object.num should not change" do
+        @object.increment
+      end
+    end
+
+    assert_equal "@object.num should not change.\n\"@object.num\" did change to 1", error.message
+  end
 end
 
 # Setup and teardown callbacks.
@@ -133,7 +269,7 @@ class SetupAndTeardownTest < ActiveSupport::TestCase
   def teardown
   end
 
-  protected
+  private
 
     def reset_callback_record
       @called_back = []
@@ -158,7 +294,7 @@ class SubclassSetupAndTeardownTest < SetupAndTeardownTest
     assert_equal [:foo, :sentinel, :bar], self.class._teardown_callbacks.map(&:raw_filter)
   end
 
-  protected
+  private
     def bar
       @called_back << :bar
     end
@@ -170,7 +306,7 @@ end
 
 class TestCaseTaggedLoggingTest < ActiveSupport::TestCase
   def before_setup
-    require 'stringio'
+    require "stringio"
     @out = StringIO.new
     self.tagged_logger = ActiveSupport::TaggedLogging.new(Logger.new(@out))
     super