add tests for our minitest reporter.

railties/test/test_unit/reporter_test.rb

@@ -0,0 +1,76 @@
+require 'abstract_unit'
+require 'rails/test_unit/reporter'
+
+class TestUnitReporterTest < ActiveSupport::TestCase
+  class ExampleTest < Minitest::Test
+    def woot; end
+  end
+
+  setup do
+    @output = StringIO.new
+    @reporter = Rails::TestUnitReporter.new @output
+  end
+
+  test "prints rerun snippet to run a single failed test" do
+    @reporter.results << failed_test
+    @reporter.report
+
+    assert_match %r{^bin/rails test .*test/test_unit/reporter_test.rb:6$}, @output.string
+    assert_rerun_snippet_count 1
+  end
+
+  test "prints rerun snippet for every failed test" do
+    @reporter.results << failed_test
+    @reporter.results << failed_test
+    @reporter.results << failed_test
+    @reporter.report
+
+    assert_rerun_snippet_count 3
+  end
+
+  test "does not print snippet for successful and skipped tests" do
+    skip "confirm the expected behavior with Arthur"
+    @reporter.results << passing_test
+    @reporter.results << skipped_test
+    @reporter.report
+    assert_rerun_snippet_count 0
+  end
+
+  test "prints rerun snippet for skipped tests if run in verbose mode" do
+    skip "confirm the expected behavior with Arthur"
+    verbose = Rails::TestUnitReporter.new @output, verbose: true
+    verbose.results << skipped_test
+    verbose.report
+
+    assert_rerun_snippet_count 1
+  end
+
+  private
+  def assert_rerun_snippet_count(snippet_count)
+    assert_equal snippet_count, @output.string.scan(%r{^bin/rails test }).size
+  end
+
+  def failed_test
+    ft = ExampleTest.new(:woot)
+    ft.failures << begin
+                     raise Minitest::Assertion, "boo"
+                   rescue Minitest::Assertion => e
+                     e
+                   end
+    ft
+  end
+
+  def passing_test
+    ExampleTest.new(:woot)
+  end
+
+  def skipped_test
+    st = ExampleTest.new(:woot)
+    st.failures << begin
+                     raise Minitest::Skip
+                   rescue Minitest::Assertion => e
+                     e
+                   end
+    st
+  end
+end