[ruby/rdoc] Add test coverage for -C flag

https://github.com/ruby/rdoc/commit/564be08f4b

test/rdoc/test_rdoc_options.rb

@@ -209,6 +209,13 @@ rdoc_include:
     assert @options.force_update
   end
 
+  def test_parse_coverage_C
+    @options.parse %w[-C]
+
+    assert @options.coverage_report
+    assert @options.force_update
+  end
+
   def test_parse_coverage_no
     @options.parse %w[--no-dcov]
 
@@ -221,6 +228,19 @@ rdoc_include:
     assert_equal 1, @options.coverage_report
   end
 
+  def test_parse_coverage_C_level_1
+    @options.parse %w[-C1]
+
+    assert_equal 1, @options.coverage_report
+  end
+
+  def test_parse_coverage_C_level_0
+    @options.parse %w[-C0]
+
+    assert_equal 0, @options.coverage_report
+    assert @options.force_update
+  end
+
   def test_parse_dash_p
     out, err = capture_output do
       @options.parse %w[-p]