This is a testharness.js-based test.
Harness Error. harness_status.status = 1 , harness_status.message = 6 duplicate test names: "WritableStreamDefaultWriter.prototype.desiredSize enforces a brand check", "WritableStreamDefaultWriter.prototype.closed enforces a brand check", "WritableStreamDefaultWriter.prototype.ready enforces a brand check", "WritableStreamDefaultWriter.prototype.abort enforces a brand check", "WritableStreamDefaultWriter.prototype.write enforces a brand check", "WritableStreamDefaultWriter.prototype.close enforces a brand check"
PASS WritableStreamDefaultWriter.prototype.desiredSize enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.closed enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.ready enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.abort enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.write enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.close enforces a brand check 
PASS Untitled 
PASS WritableStreamDefaultWriter.prototype.desiredSize enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.closed enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.ready enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.abort enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.write enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.close enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.desiredSize enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.closed enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.ready enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.abort enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.write enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.close enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.desiredSize enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.closed enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.ready enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.abort enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.write enforces a brand check 
PASS WritableStreamDefaultWriter.prototype.close enforces a brand check 
Harness: the test ran to completion.