3 files changed, 11 insertions, 5 deletions
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index e61deb1080..bffff07089 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -253,7 +253,8 @@ class FixturesTest < ActiveRecord::TestCase
   end
 
   def test_fixtures_are_set_up_with_database_env_variable
-    ENV.stubs(:[]).with("DATABASE_URL").returns("sqlite3:///:memory:")
+    db_url_tmp = ENV['DATABASE_URL']
+    ENV['DATABASE_URL'] = "sqlite3:///:memory:"
     ActiveRecord::Base.stubs(:configurations).returns({})
     test_case = Class.new(ActiveRecord::TestCase) do
       fixtures :accounts
@@ -266,6 +267,8 @@ class FixturesTest < ActiveRecord::TestCase
     result = test_case.new(:test_fixtures).run
 
     assert result.passed?, "Expected #{result.name} to pass:\n#{result}"
+  ensure
+    ENV['DATABASE_URL'] = db_url_tmp
   end
 end
 
diff --git a/activerecord/test/cases/relation/delegation_test.rb b/activerecord/test/cases/relation/delegation_test.rb
index 71ade0bcc2..c171c5e14e 100644
--- a/activerecord/test/cases/relation/delegation_test.rb
+++ b/activerecord/test/cases/relation/delegation_test.rb
@@ -9,10 +9,11 @@ module ActiveRecord
     def assert_responds(target, method)
       assert target.respond_to?(method)
       assert_nothing_raised do
-        case target.to_a.method(method).arity
-        when 0
+        method_arity = target.to_a.method(method).arity
+
+        if method_arity.zero?
           target.send(method)
-        when -1
+        elsif method_arity < 0
           if method == :shuffle!
             target.send(method)
           else
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index 17206ffe99..980981903a 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -421,7 +421,9 @@ class TransactionTest < ActiveRecord::TestCase
     topic = Topic.new(:title => 'test')
     topic.freeze
     e = assert_raise(RuntimeError) { topic.save }
-    assert_equal "can't modify frozen Hash", e.message
+    assert_match(/frozen/i, e.message) # Not good enough, but we can't do much
+                                       # about it since there is no specific error
+                                       # for frozen objects.
     assert !topic.persisted?, 'not persisted'
     assert_nil topic.id
     assert topic.frozen?, 'not frozen'