feat: Support configuring MT_COMPAT in the minitest template (#234)

toys-core/.toys/.toys.rb

@@ -9,7 +9,7 @@
 
 expand :clean, paths: :gitignore
 
-expand :minitest, libs: ["lib", "test"], bundler: true
+expand :minitest, libs: ["lib", "test"], bundler: true, mt_compat: true
 
 tool "test" do
   flag :integration_tests, "--integration-tests", "--integration", desc: "Enable integration tests"

toys/.toys/.toys.rb

@@ -9,7 +9,7 @@
 
 expand :clean, paths: :gitignore
 
-expand :minitest, libs: ["lib", "test"], bundler: true
+expand :minitest, libs: ["lib", "test"], bundler: true, mt_compat: true
 
 tool "test" do
   flag :integration_tests, "--integration-tests", "--integration", desc: "Enable integration tests"

toys/lib/toys/templates/minitest.rb

@@ -55,6 +55,10 @@ class Minitest
       #     enabled. See the documentation for the
       #     [bundler mixin](https://dazuma.github.io/toys/gems/toys-core/latest/Toys/StandardMixins/Bundler)
       #     for information on available options.
+      # @param mt_compat [boolean] If set to `true` or `false`, sets the
+      #     `MT_COMPAT` environment variable accordingly. This may be required
+      #     for certain older Minitest plugins. Optional. If not present, keeps
+      #     any current setting.
       # @param context_directory [String] A custom context directory to use
       #     when executing this tool.
       #
@@ -66,6 +70,7 @@ def initialize(name: nil,
                      verbose: false,
                      warnings: true,
                      bundler: false,
+                     mt_compat: nil,
                      context_directory: nil)
         @name = name
         @gem_version = gem_version
@@ -75,6 +80,7 @@ def initialize(name: nil,
         @verbose = verbose
         @warnings = warnings
         @bundler = bundler
+        @mt_compat = mt_compat
         @context_directory = context_directory
       end
 
@@ -160,6 +166,18 @@ def initialize(name: nil,
       #
       attr_writer :bundler
 
+      ##
+      # Adjust the `MT_COMPAT` environment variable when running tests. This
+      # setting may be necessary for certain older Minitest plugins.
+      #
+      # Pass `true` to enable compat mode, `false` to disable it, or `nil` to
+      # use any ambient setting from the current environment.
+      #
+      # @param value [true,false,nil]
+      # @return [true,false,nil]
+      #
+      attr_writer :mt_compat
+
       ##
       # Use bundler for this tool.
       #
@@ -195,6 +213,11 @@ def use_bundler(**opts)
       #
       attr_reader :context_directory
 
+      ##
+      # @private
+      #
+      attr_reader :mt_compat
+
       ##
       # @private
       #
@@ -287,7 +310,10 @@ def bundler_settings
               ruby_args << "--name" << name if name
               ruby_args << "--exclude" << exclude if exclude
 
-              result = exec_ruby(ruby_args)
+              env = {}
+              env["MT_COMPAT"] = template.mt_compat ? "true" : nil unless template.mt_compat.nil?
+
+              result = exec_ruby(ruby_args, env: env)
               if result.error?
                 logger.error("Minitest failed!")
                 exit(result.exit_code)

toys/test/minitest-cases/mt-compat/foo.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require "minitest/autorun"
+
+describe "foo" do
+  it "sets MT_COMPAT" do
+    assert_equal("true", ENV["MT_COMPAT"])
+  end
+end

toys/test/test_minitest.rb

@@ -68,6 +68,14 @@
       assert_equal(false, template.warnings)
     end
 
+    it "handles the mt_compat field" do
+      assert_nil(template.mt_compat)
+      template.mt_compat = false
+      assert_equal(false, template.mt_compat)
+      template.mt_compat = true
+      assert_equal(true, template.mt_compat)
+    end
+
     it "handles the gem_version field with bundler" do
       template.use_bundler
       assert_equal([], template.gem_version)
@@ -166,6 +174,55 @@
       assert_match(/1 failure/, out)
     end
 
+    it "passes MT_COMPAT" do
+      dir = cases_dir
+      loader.add_block do
+        set_context_directory dir
+        expand :minitest, files: "mt-compat/*.rb"
+      end
+      expected_failures = ENV["MT_COMPAT"] ? 0 : 1
+      out, _err = capture_subprocess_io do
+        assert_equal(expected_failures, cli.run("test"))
+      end
+      assert_match(/#{expected_failures} failure/, out)
+    end
+
+    it "sets MT_COMPAT" do
+      dir = cases_dir
+      loader.add_block do
+        set_context_directory dir
+        expand :minitest, files: "mt-compat/*.rb", mt_compat: true
+      end
+      old_mt_compat = ENV["MT_COMPAT"]
+      begin
+        out, _err = capture_subprocess_io do
+          ENV["MT_COMPAT"] = nil
+          assert_equal(0, cli.run("test"))
+        end
+      ensure
+        ENV["MT_COMPAT"] = old_mt_compat
+      end
+      assert_match(/0 failures/, out)
+    end
+
+    it "clears MT_COMPAT" do
+      dir = cases_dir
+      loader.add_block do
+        set_context_directory dir
+        expand :minitest, files: "mt-compat/*.rb", mt_compat: false
+      end
+      old_mt_compat = ENV["MT_COMPAT"]
+      begin
+        out, _err = capture_subprocess_io do
+          ENV["MT_COMPAT"] = "true"
+          assert_equal(1, cli.run("test"))
+        end
+      ensure
+        ENV["MT_COMPAT"] = old_mt_compat
+      end
+      assert_match(/1 failure/, out)
+    end
+
     it "supports input streams" do
       dir = "#{cases_dir}/stream"
       args = ["--disable=gems", Toys.executable_path, "test"]