* Don't eagerly require Rails' minitest plugin.

By making the Rails minitest behave like a standard minitest plugin
we're much more likely to not break when people use other minitest
plugins. Like minitest-focus and pride.

To do this, we need to behave like minitest: require files up front
and then perform the plugin behavior via the at_exit hook.
This also saves us a fair bit of wrangling with test file loading.

Finally, since the environment and warnings options have to be applied
as early as possible, and since minitest loads plugins at_exit, they
have to be moved to the test command.

* Don't expect the root method.

It's likely this worked because we eagerly loaded the Rails minitest plugin
and that somehow defined a root method on `Rails`.

* Assign a backtrace to failed exceptions.

Otherwise Minitest pukes when attempting to filter the backtrace (which
Rails' backtrace cleaner then removes).

Means the exception message test has to be revised too.

This is likely caused by the rails minitest plugin now being loaded for
these tests and assigning a default backtrace cleaner.

1 files changed, 49 insertions, 0 deletions

diff --git a/railties/lib/minitest/rails_plugin.rb b/railties/lib/minitest/rails_plugin.rb
new file mode 100644
index 0000000000..fec9ae64d8
--- /dev/null
+++ b/railties/lib/minitest/rails_plugin.rb
@@ -0,0 +1,49 @@
+require "active_support/core_ext/module/attribute_accessors"
+require "rails/test_unit/reporter"
+
+module Minitest
+  class SuppressedSummaryReporter < SummaryReporter
+    # Disable extra failure output after a run if output is inline.
+    def aggregated_results(*)
+      super unless options[:output_inline]
+    end
+  end
+
+  def self.plugin_rails_options(opts, options)
+    opts.on("-b", "--backtrace", "Show the complete backtrace") do
+      options[:full_backtrace] = true
+    end
+
+    opts.on("-d", "--defer-output", "Output test failures and errors after the test run") do
+      options[:output_inline] = false
+    end
+
+    opts.on("-f", "--fail-fast", "Abort test run on first failure or error") do
+      options[:fail_fast] = true
+    end
+
+    opts.on("-c", "--[no-]color", "Enable color in the output") do |value|
+      options[:color] = value
+    end
+
+    options[:color] = true
+    options[:output_inline] = true
+  end
+
+  # Owes great inspiration to test runner trailblazers like RSpec,
+  # minitest-reporters, maxitest and others.
+  def self.plugin_rails_init(options)
+    unless options[:full_backtrace] || ENV["BACKTRACE"]
+      # Plugin can run without Rails loaded, check before filtering.
+      Minitest.backtrace_filter = ::Rails.backtrace_cleaner if ::Rails.respond_to?(:backtrace_cleaner)
+    end
+
+    # Replace progress reporter for colors.
+    reporter.reporters.delete_if { |reporter| reporter.kind_of?(SummaryReporter) || reporter.kind_of?(ProgressReporter) }
+    reporter << SuppressedSummaryReporter.new(options[:io], options)
+    reporter << ::Rails::TestUnitReporter.new(options[:io], options)
+  end
+
+  # Backwardscompatibility with Rails 5.0 generated plugin test scripts
+  mattr_reader :run_via, default: {}
+end