CSS Transforms 2: Web Platform Tests for translate,rotate,scale parsing

third_party/WebKit/LayoutTests/external/wpt/css/css-transforms-2/resources/testcommon.js

+'use strict';

[suzyh_UTC10 (ex-contributor), 2017/05/22 01:11:45]

Consider naming this file something like testcommon-parsing.js or
parsing-testcommon.js and/or rename the functions to make it obvious that they
are specifically related to parsing.

[Eric Willigers, 2017/05/22 07:13:39]

Done.

+
+function assert_valid_value(property, value) {

[suzyh_UTC10 (ex-contributor), 2017/05/22 01:11:45]

I find it slightly surprising that a function named 'assert_...' actually
creates tests, where the testharness format is of tests containing calls to
assert_* functions. Perhaps test_valid_value or test_valid_value_for_parsing?

[Eric Willigers, 2017/05/22 07:13:40]

Done.

I also came across another option, but I don't find it any clearer:
https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/external/...
uses the terminology generate_tests.

+    var stringifiedValue = JSON.stringify(value);
+
+    test(function(){
+        var div = document.createElement('div');
+        div.style[property] = value;
+        assert_not_equals(div.style[property], "");
+    }, "e.style['" + property + "'] = " + stringifiedValue + " should set the value");

[suzyh_UTC10 (ex-contributor), 2017/05/22 01:11:44]

Is 'sets the value' exactly synonymous with 'parses as a valid value', or is
this test doing something subtly different from testing parsing?

[Eric Willigers, 2017/05/22 07:13:39]

I have changed the function to accept an optional third argument: the canonical
serialized form.

Two tests using the third argument have been appended to
translate-parsing-valid.html

+
+    test(function(){
+        var div = document.createElement('div');
+        div.style[property] = value;
+        assert_equals(div.style[property], value);
+    }, "Serialization should round-trip after setting e.style['" + property + "'] = " + stringifiedValue);

[suzyh_UTC10 (ex-contributor), 2017/05/22 01:11:45]

Are we likely to want to test that X is a valid value, but it serializes
differently, so would come out differently here?

+}
+
+function assert_invalid_value(property, value) {
+    var stringifiedValue = JSON.stringify(value);
+
+    test(function(){
+        var div = document.createElement('div');
+        div.style[property] = value;
+        assert_equals(div.style[property], "");
+    }, "e.style['" + property + "'] = " + stringifiedValue + " should not set the value");

[suzyh_UTC10 (ex-contributor), 2017/05/22 01:11:45]

I find this test description (and to a lesser extent, the equivalent one under
assert_valid_value) difficult to understand. That is, if I accidentally made
this test fail, I'm not sure I'd know what to do as a result of reading this
description. I think my main concern is that I would come across this error and
think "should not set the value of what?"

+}