1 files changed, 78 insertions, 0 deletions
diff --git a/activesupport/test/testing/constant_lookup_test.rb b/activesupport/test/testing/constant_lookup_test.rb
new file mode 100644
index 0000000000..37b7822950
--- /dev/null
+++ b/activesupport/test/testing/constant_lookup_test.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "dependencies_test_helpers"
+
+class Foo; end
+class Bar < Foo
+  def index; end
+  def self.index; end
+end
+module FooBar; end
+
+class ConstantLookupTest < ActiveSupport::TestCase
+  include ActiveSupport::Testing::ConstantLookup
+  include DependenciesTestHelpers
+
+  def find_foo(name)
+    self.class.determine_constant_from_test_name(name) do |constant|
+      Class === constant && constant < Foo
+    end
+  end
+
+  def find_module(name)
+    self.class.determine_constant_from_test_name(name) do |constant|
+      Module === constant
+    end
+  end
+
+  def test_find_bar_from_foo
+    assert_equal Bar, find_foo("Bar")
+    assert_equal Bar, find_foo("Bar::index")
+    assert_equal Bar, find_foo("Bar::index::authenticated")
+    assert_equal Bar, find_foo("BarTest")
+    assert_equal Bar, find_foo("BarTest::index")
+    assert_equal Bar, find_foo("BarTest::index::authenticated")
+  end
+
+  def test_find_module
+    assert_equal FooBar, find_module("FooBar")
+    assert_equal FooBar, find_module("FooBar::index")
+    assert_equal FooBar, find_module("FooBar::index::authenticated")
+    assert_equal FooBar, find_module("FooBarTest")
+    assert_equal FooBar, find_module("FooBarTest::index")
+    assert_equal FooBar, find_module("FooBarTest::index::authenticated")
+  end
+
+  def test_returns_nil_when_cant_find_foo
+    assert_nil find_foo("DoesntExist")
+    assert_nil find_foo("DoesntExistTest")
+    assert_nil find_foo("DoesntExist::Nadda")
+    assert_nil find_foo("DoesntExist::Nadda::Nope")
+    assert_nil find_foo("DoesntExist::Nadda::Nope::NotHere")
+  end
+
+  def test_returns_nil_when_cant_find_module
+    assert_nil find_module("DoesntExist")
+    assert_nil find_module("DoesntExistTest")
+    assert_nil find_module("DoesntExist::Nadda")
+    assert_nil find_module("DoesntExist::Nadda::Nope")
+    assert_nil find_module("DoesntExist::Nadda::Nope::NotHere")
+  end
+
+  def test_does_not_swallow_exception_on_no_method_error
+    assert_raises(NoMethodError) {
+      with_autoloading_fixtures {
+        self.class.determine_constant_from_test_name("RaisesNoMethodError")
+      }
+    }
+  end
+
+  def test_does_not_swallow_exception_on_no_name_error_within_constant
+    assert_raises(NameError) do
+      with_autoloading_fixtures do
+        self.class.determine_constant_from_test_name("RaisesNameError")
+      end
+    end
+  end
+end