Reject encodings determined at runtime as source code encodings

The encodings determined at runtime are affected by the runtime
environment, such as the OS and locale, while the file contents are
not.

1 files changed, 28 insertions, 0 deletions

diff --git a/test/ruby/test_parse.rb b/test/ruby/test_parse.rb
index c2f02ff809..858c623bcc 100644
--- a/test/ruby/test_parse.rb
+++ b/test/ruby/test_parse.rb
@@ -767,6 +767,34 @@ x = __ENCODING__
       END
     end
     assert_equal(__ENCODING__, x)
+
+    assert_raise(ArgumentError) do
+      EnvUtil.with_default_external(Encoding::US_ASCII) {eval <<-END, nil, __FILE__, __LINE__+1}
+# coding = external
+x = __ENCODING__
+      END
+    end
+
+    assert_raise(ArgumentError) do
+      EnvUtil.with_default_internal(Encoding::US_ASCII) {eval <<-END, nil, __FILE__, __LINE__+1}
+# coding = internal
+x = __ENCODING__
+      END
+    end
+
+    assert_raise(ArgumentError) do
+      eval <<-END, nil, __FILE__, __LINE__+1
+# coding = filesystem
+x = __ENCODING__
+      END
+    end
+
+    assert_raise(ArgumentError) do
+      eval <<-END, nil, __FILE__, __LINE__+1
+# coding = locale
+x = __ENCODING__
+      END
+    end
   end
 
   def test_utf8_bom