Add --fail-no-examples option: fail if no RSpec examples

Default behavior not changed.

Author: xmik

features/command_line/fail_no_examples.feature

@@ -0,0 +1,47 @@
+Feature: `--fail-no-examples` option
+
+  Use the `--fail-no-examples` option to make RSpec return non zero exit status
+   when there are 0 examples.
+
+  Background:
+    Given a file named "spec/spec_helper.rb" with:
+      """ruby
+      RSpec.configure do |c|
+        # no options here
+      end
+      """
+
+  Scenario: A failing spec example
+    Given a file named "example_spec.rb" with:
+      """ruby
+      RSpec.describe "something" do
+        it "fails" do
+          fail
+        end
+      end
+      """
+    When I run `rspec --fail-no-examples example_spec.rb`
+    Then the exit status should be 1
+
+  Scenario: A passing spec example
+    Given a file named "example_spec.rb" with:
+      """ruby
+      require 'spec_helper'
+      RSpec.describe "something" do
+        it "succeeds" do
+          true
+        end
+      end
+      """
+    When I run `rspec --fail-no-examples example_spec.rb`
+    Then the exit status should be 0
+
+  Scenario: No examples
+    Given a file named "example_spec.rb" with:
+      """ruby
+      require 'spec_helper'
+      RSpec.describe "something" do
+      end
+      """
+    When I run `rspec --fail-no-examples example_spec.rb`
+    Then the exit status should be 1

features/configuration/fail_no_examples.feature

@@ -0,0 +1,49 @@
+Feature: fail no examples
+
+  Use the `fail_no_examples` option to make RSpec return non zero exit status
+   when there are 0 examples.
+
+  ```ruby
+  RSpec.configure { |c| c.fail_no_examples = true }
+  ```
+
+  Background:
+    Given a file named "spec/spec_helper.rb" with:
+      """ruby
+      RSpec.configure { |c| c.fail_no_examples = true }
+      """
+
+  Scenario: A failing spec example
+    Given a file named "spec/example_spec.rb" with:
+      """ruby
+      RSpec.describe "something" do
+        it "fails" do
+          fail
+        end
+      end
+      """
+    When I run `rspec spec/example_spec.rb`
+    Then the exit status should be 1
+
+  Scenario: A passing spec example
+    Given a file named "spec/example_spec.rb" with:
+      """ruby
+      require 'spec_helper'
+      RSpec.describe "something" do
+        it "succeeds" do
+          true
+        end
+      end
+      """
+    When I run `rspec spec/example_spec.rb`
+    Then the exit status should be 0
+
+  Scenario: No examples
+    Given a file named "spec/example_spec.rb" with:
+      """ruby
+      require 'spec_helper'
+      RSpec.describe "something" do
+      end
+      """
+    When I run `rspec spec/example_spec.rb`
+    Then the exit status should be 1

lib/rspec/core/configuration.rb

@@ -199,6 +199,10 @@ def only_failures_but_not_configured?
       # The exit code to return if there are any failures (default: 1).
       add_setting :failure_exit_code
 
+      # @macro add_setting
+      # Whether or not to fail when there are no RSpec examples (default: false).
+      add_setting :fail_no_examples
+
       # @macro define_reader
       # Indicates files configured to be required.
       define_reader :requires
@@ -425,6 +429,7 @@ def initialize
         @pattern = '**{,/*/**}/*_spec.rb'
         @exclude_pattern = ''
         @failure_exit_code = 1
+        @fail_no_examples = false
         @spec_files_loaded = false
 
         @backtrace_formatter = BacktraceFormatter.new

lib/rspec/core/drb.rb

@@ -40,13 +40,14 @@ def initialize(submitted_options, filter_manager)
 
       def options
         argv = []
-        argv << "--color"        if @submitted_options[:color]
-        argv << "--profile"      if @submitted_options[:profile_examples]
-        argv << "--backtrace"    if @submitted_options[:full_backtrace]
-        argv << "--tty"          if @submitted_options[:tty]
-        argv << "--fail-fast"    if @submitted_options[:fail_fast]
-        argv << "--options"      << @submitted_options[:custom_options_file] if @submitted_options[:custom_options_file]
-        argv << "--order"        << @submitted_options[:order]               if @submitted_options[:order]
+        argv << "--color"            if @submitted_options[:color]
+        argv << "--profile"          if @submitted_options[:profile_examples]
+        argv << "--backtrace"        if @submitted_options[:full_backtrace]
+        argv << "--tty"              if @submitted_options[:tty]
+        argv << "--fail-fast"        if @submitted_options[:fail_fast]
+        argv << "--fail-no-examples" if @submitted_options[:fail_no_examples]
+        argv << "--options"          << @submitted_options[:custom_options_file] if @submitted_options[:custom_options_file]
+        argv << "--order"            << @submitted_options[:order]               if @submitted_options[:order]
 
         add_failure_exit_code(argv)
         add_full_description(argv)

lib/rspec/core/option_parser.rb

@@ -93,6 +93,11 @@ def parser(options)
           options[:failure_exit_code] = code
         end
 
+        parser.on('--fail-no-examples', 'Whether or not to fail when there are'\
+          ' no RSpec examples. Defaults to `false`.') do |_o|
+          options[:fail_no_examples] = true
+        end
+
         parser.on('--dry-run', 'Print the formatter output of your suite without',
                   '  running any examples or hooks') do |_o|
           options[:dry_run] = true

lib/rspec/core/rake_task.rb

@@ -38,10 +38,14 @@ class RakeTask < ::Rake::TaskLib
       # Defaults to `nil`.
       attr_accessor :exclude_pattern
 
-      # Whether or not to fail Rake when an error occurs (typically when
+      # Whether or not to fail Rake task when an error occurs (typically when
       # examples fail). Defaults to `true`.
       attr_accessor :fail_on_error
 
+      # Whether or not to fail Rake task when there are no RSpec examples.
+      # Defaults to `false`.
+      attr_accessor :fail_no_examples
+
       # A message to print to stderr when there are failures.
       attr_accessor :failure_message
 
@@ -60,13 +64,14 @@ class RakeTask < ::Rake::TaskLib
       attr_accessor :rspec_opts
 
       def initialize(*args, &task_block)
-        @name          = args.shift || :spec
-        @ruby_opts     = nil
-        @rspec_opts    = nil
-        @verbose       = true
-        @fail_on_error = true
-        @rspec_path    = DEFAULT_RSPEC_PATH
-        @pattern       = DEFAULT_PATTERN
+        @name             = args.shift || :spec
+        @ruby_opts        = nil
+        @rspec_opts       = nil
+        @verbose          = true
+        @fail_on_error    = true
+        @fail_no_examples = false
+        @rspec_path       = DEFAULT_RSPEC_PATH
+        @pattern          = DEFAULT_PATTERN
 
         define(args, &task_block)
       end

lib/rspec/core/runner.rb

@@ -110,6 +110,9 @@ def setup(err, out)
       def run_specs(example_groups)
         @configuration.reporter.report(@world.example_count(example_groups)) do |reporter|
           @configuration.with_suite_hooks do
+            if @world.example_count(example_groups) == 0 && @configuration.fail_no_examples
+              return 1
+            end
             example_groups.map { |g| g.run(reporter) }.all? ? 0 : @configuration.failure_exit_code
           end
         end

spec/rspec/core/configuration_options_spec.rb

@@ -296,6 +296,16 @@
     end
   end
 
+  describe "--fail-no-examples" do
+    it "defaults to false" do
+      expect(parse_options[:fail_no_examples]).to be_falsey
+    end
+
+    it "sets fail_no_examples on config" do
+      expect(parse_options("--fail-no-examples")[:fail_no_examples]).to be_truthy
+    end
+  end
+
   describe "--dry-run" do
     it "defaults to false" do
       expect(parse_options[:dry_run]).to be_falsey

spec/rspec/core/rake_task_spec.rb

@@ -112,6 +112,13 @@ def silence_output(&block)
       end
     end
 
+    context 'with --fail-no-examples set' do
+      it 'adds the rspec_opts' do
+        task.rspec_opts = "--fail-no-examples"
+        expect(spec_command).to match(/#{task.rspec_path}.*--fail-no-examples/)
+      end
+    end
+
     context 'with verbose enabled' do
       it 'prints the command only to stdout for passing specs', :slow do
         expect {