t.Errorf("for %s expected Content-Length header of %q; got %q", url, expected, cl)
		}
		if tl, expected := len(res.TransferEncoding), 0; tl != expected {
			t.Errorf("for %s expected len(res.TransferEncoding) of %d; got %d (%v)",
				url, expected, tl, res.TransferEncoding)
		}
		res.Body.Close()
	}

	// Verify that ErrContentLength is returned
	url := ts.URL + "/?overwrite=1"

// This type is used to avoid extra allocations from cloning and/or populating
// the response Header map and all its 1-element slices.
type extraHeader struct {
	contentType      string
	connection       string
	transferEncoding string
	date             []byte // written if not nil
	contentLength    []byte // written if not nil
}

// Sorted the same as extraHeader.Write's loop.
var extraHeaderKeys = [][]byte{

		addCustomHeaders(req, testCase.headers)

		// Inject faults if specified in testCase.fault
		switch testCase.fault {
		case MissingContentLength:
			req.ContentLength = -1
			req.TransferEncoding = []string{}
		case TooBigObject:
			req.ContentLength = globalMaxObjectSize + 1
		}
		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic of the handler.