+ Added -Werror to raise on any warning output. (byroot)

+ Added UnexpectedWarning as a failure summary type, added count to output if activated.

Also allows for -Wall or -W or -W<category>.
Fixed all tests to pass vanilla + -Werror.

Found (but not yet fixed) tests that currently fail vanilla if `$-w=nil`.

[git-p4: depot-paths = "//src/minitest/dev/": change = 14142]

Manifest.txt

@@ -10,6 +10,7 @@ lib/minitest/assertions.rb
 lib/minitest/autorun.rb
 lib/minitest/benchmark.rb
 lib/minitest/compress.rb
+lib/minitest/error_on_warning.rb
 lib/minitest/expectations.rb
 lib/minitest/hell.rb
 lib/minitest/manual_plugins.rb

lib/minitest.rb

@@ -253,6 +253,20 @@ def self.process_args args = [] # :nodoc:
         options[:skip] = s.chars.to_a
       end
 
+      ruby27plus = ::Warning.respond_to?(:[]=)
+
+      opts.on "-W[error]", String, "Turn Ruby warnings into errors" do |s|
+        options[:Werror] = true
+        case s
+        when "error", "all", nil then
+          require "minitest/error_on_warning"
+          $VERBOSE = true
+          ::Warning[:deprecated] = true if ruby27plus
+        else
+          ::Warning[s.to_sym] = true if ruby27plus # check validity of category
+        end
+      end
+
       unless extensions.empty?
         opts.separator ""
         opts.separator "Known extensions: #{extensions.join(", ")}"
@@ -782,6 +796,11 @@ class StatisticsReporter < Reporter
 
     attr_accessor :errors
 
+    ##
+    # Total number of tests that warned.
+
+    attr_accessor :warnings
+
     ##
     # Total number of tests that where skipped.
 
@@ -797,6 +816,7 @@ def initialize io = $stdout, options = {} # :nodoc:
       self.total_time = nil
       self.failures   = nil
       self.errors     = nil
+      self.warnings   = nil
       self.skips      = nil
     end
 
@@ -825,6 +845,7 @@ def report
       self.total_time = Minitest.clock_time - start_time
       self.failures   = aggregate[Assertion].size
       self.errors     = aggregate[UnexpectedError].size
+      self.warnings   = aggregate[UnexpectedWarning].size
       self.skips      = aggregate[Skip].size
     end
   end
@@ -900,6 +921,8 @@ def summary # :nodoc:
         results.any?(&:skipped?) unless
         options[:verbose] or options[:show_skips] or ENV["MT_NO_SKIP_MSG"]
 
+      extra.prepend ", %d warnings" % [warnings] if options[:Werror]
+
       "%d runs, %d assertions, %d failures, %d errors, %d skips%s" %
         [count, assertions, failures, errors, skips, extra]
     end
@@ -1034,6 +1057,15 @@ def result_label # :nodoc:
     end
   end
 
+  ##
+  # Assertion raised on warning when running in -Werror mode.
+
+  class UnexpectedWarning < Assertion
+    def result_label # :nodoc:
+      "Warning"
+    end
+  end
+
   ##
   # Provides a simple set of guards that you can use in your tests
   # to skip execution if it is not applicable. These methods are
@@ -1107,7 +1139,7 @@ def windows? platform = RUBY_PLATFORM
 
   class BacktraceFilter
 
-    MT_RE = %r%lib/minitest% #:nodoc:
+    MT_RE = %r%lib/minitest|internal:warning% #:nodoc:
 
     attr_accessor :regexp
 

lib/minitest/error_on_warning.rb

@@ -0,0 +1,11 @@
+module Minitest
+
+  module ErrorOnWarning
+    def warn(message, category: nil)
+      message = "[#{category}] #{message}" if category
+      raise UnexpectedWarning, message
+    end
+  end
+
+  ::Warning.singleton_class.prepend(ErrorOnWarning)
+end

test/minitest/metametameta.rb

@@ -25,8 +25,19 @@ def with_backtrace_filter filter
       end
     end
   end
-end
 
+  def error_on_warn?
+    defined?(Minitest::ErrorOnWarning)
+  end
+
+  def assert_deprecation re = /DEPRECATED/
+    assert_output "", re do
+      yield
+    end
+  rescue Minitest::UnexpectedWarning => e # raised if -Werror was used
+    assert_match re, e.message
+  end
+end
 
 class FakeNamedTest < Minitest::Test
   @@count = 0

test/minitest/test_minitest_assertions.rb

@@ -1,6 +1,7 @@
 # encoding: UTF-8
 
 require "minitest/autorun"
+require_relative "metametameta"
 
 if defined? Encoding then
   e = Encoding.default_external
@@ -33,7 +34,6 @@ class TestMinitestAssertions < Minitest::Test
 
   class DummyTest
     include Minitest::Assertions
-    # include Minitest::Reportable # TODO: why do I really need this?
 
     attr_accessor :assertions, :failure
 
@@ -58,15 +58,6 @@ def teardown
                  "expected #{@assertion_count} assertions to be fired during the test, not #{@tc.assertions}")
   end
 
-  def assert_deprecated name
-    dep = /DEPRECATED: #{name}. From #{__FILE__}:\d+(?::.*)?/
-    dep = "" if $-w.nil?
-
-    assert_output nil, dep do
-      yield
-    end
-  end
-
   def assert_triggered expected, klass = Minitest::Assertion
     e = assert_raises klass do
       yield
@@ -301,7 +292,7 @@ def test_assert_equal_does_not_allow_lhs_nil
       err_re = /Use assert_nil if expecting nil from .*test_minitest_\w+.rb/
       err_re = "" if $-w.nil?
 
-      assert_output "", err_re do
+      assert_deprecation err_re do
         @tc.assert_equal nil, nil
       end
     end
@@ -975,16 +966,24 @@ def test_assert_same_triggered
   end
 
   def test_assert_send
-    assert_deprecated :assert_send do
+    @assertion_count = 0 if error_on_warn?
+    assert_deprecation(/DEPRECATED: assert_send/) do
       @tc.assert_send [1, :<, 2]
     end
   end
 
   def test_assert_send_bad
-    assert_deprecated :assert_send do
-      assert_triggered "Expected 1.>(*[2]) to return true." do
+    if error_on_warn? then
+      @assertion_count = 0
+      assert_deprecation(/DEPRECATED: assert_send/) do
         @tc.assert_send [1, :>, 2]
       end
+    else
+      assert_triggered "Expected 1.>(*[2]) to return true." do
+        assert_deprecation(/DEPRECATED: assert_send/) do
+          @tc.assert_send [1, :>, 2]
+        end
+      end
     end
   end
 
@@ -1502,7 +1501,7 @@ def test_skip_until
     d0 = Time.now
     d1 = d0 + 86_400 # I am an idiot
 
-    assert_output "", /Stale skip_until \"not yet\" at .*?:\d+$/ do
+    assert_deprecation(/Stale skip_until \"not yet\" at .*?:\d+$/) do
       assert_skip_until d0, "not yet"
     end
 

test/minitest/test_minitest_mock.rb

@@ -423,10 +423,12 @@ def test_mock_block_is_passed_keyword_args__args__old_style_both
       arg1, arg2, arg3 = :bar, [1, 2, 3], { :a => "a" }
       mock = Minitest::Mock.new
 
-      assert_output nil, /Using MT_KWARGS_HAC. yet passing kwargs/ do
+      assert_deprecation(/Using MT_KWARGS_HAC. yet passing kwargs/) do
         mock.expect :foo, nil, [{}], k1: arg1, k2: arg2, k3: arg3
       end
 
+      skip "-Werror" if error_on_warn? # mock above raised, so this is dead
+
       mock.foo({}, k1: arg1, k2: arg2, k3: arg3)
 
       assert_mock mock

test/minitest/test_minitest_spec.rb

@@ -284,18 +284,14 @@ def bad_pattern
   end
 
   it "needs to warn on equality with nil" do
-    @assertion_count += 1 # extra test
+    @assertion_count = 3
+    @assertion_count += 2 unless error_on_warn? # 2 extra assertions
+
+    exp = /DEPRECATED: Use assert_nil if expecting nil from .* This will fail in Minitest 6./
 
-    out, err = capture_io do
+    assert_deprecation exp do
       assert_success _(nil).must_equal(nil)
     end
-
-    exp = "DEPRECATED: Use assert_nil if expecting nil from #{__FILE__}:#{__LINE__-3}. " \
-      "This will fail in Minitest 6.\n"
-    exp = "" if $-w.nil?
-
-    assert_empty out
-    assert_equal exp, err
   end
 
   it "needs to verify floats outside a delta" do
@@ -576,7 +572,8 @@ def bad_pattern
 
     it "can NOT use must_equal in a thread. It must use expect in a thread" do
       skip "N/A" if ENV["MT_NO_EXPECTATIONS"]
-      assert_raises RuntimeError do
+
+      assert_raises RuntimeError, Minitest::UnexpectedWarning do
         capture_io do
           Thread.new { (1 + 1).must_equal 2 }.join
         end
@@ -586,9 +583,9 @@ def bad_pattern
     it "fails gracefully when expectation used outside of `it`" do
       skip "N/A" if ENV["MT_NO_EXPECTATIONS"]
 
-      @assertion_count += 1
+      @assertion_count += 2 # assert_match is compound
 
-      e = assert_raises RuntimeError do
+      e = assert_raises RuntimeError, Minitest::UnexpectedWarning do
         capture_io do
           Thread.new { # forces ctx to be nil
             describe("woot") do
@@ -598,17 +595,21 @@ def bad_pattern
         end
       end
 
-      assert_equal "Calling #must_equal outside of test.", e.message
+      exp = "Calling #must_equal outside of test."
+      exp = "DEPRECATED: global use of must_equal from" if error_on_warn?
+
+      assert_match exp, e.message
     end
 
     it "deprecates expectation used without _" do
       skip "N/A" if ENV["MT_NO_EXPECTATIONS"]
 
-      @assertion_count += 3
+      @assertion_count += 1
+      @assertion_count += 2 unless error_on_warn?
 
       exp = /DEPRECATED: global use of must_equal from/
 
-      assert_output "", exp do
+      assert_deprecation exp do
         (1 + 1).must_equal 2
       end
     end
@@ -618,12 +619,13 @@ def bad_pattern
     it "deprecates expectation used without _ with empty backtrace_filter" do
       skip "N/A" if ENV["MT_NO_EXPECTATIONS"]
 
-      @assertion_count += 3
+      @assertion_count += 1
+      @assertion_count += 2 unless error_on_warn?
 
       exp = /DEPRECATED: global use of must_equal from/
 
       with_empty_backtrace_filter do
-        assert_output "", exp do
+        assert_deprecation exp do
           (1 + 1).must_equal 2
         end
       end

test/minitest/test_minitest_test.rb

@@ -1126,19 +1126,19 @@ def test_jruby_eh
   end
 
   def test_rubinius_eh
-    assert_output "", /DEPRECATED/ do
+    assert_deprecation do
       assert self.class.rubinius? "rbx"
     end
-    assert_output "", /DEPRECATED/ do
+    assert_deprecation do
       assert self.rubinius? "rbx"
     end
   end
 
   def test_maglev_eh
-    assert_output "", /DEPRECATED/ do
+    assert_deprecation do
       assert self.class.maglev? "maglev"
     end
-    assert_output "", /DEPRECATED/ do
+    assert_deprecation do
       assert self.maglev? "maglev"
     end
   end