1 files changed, 112 insertions, 0 deletions
diff --git a/testing/web-platform/tests/mathml/support/layout-comparison.js b/testing/web-platform/tests/mathml/support/layout-comparison.js
new file mode 100644
index 0000000000..452b45006e
--- /dev/null
+++ b/testing/web-platform/tests/mathml/support/layout-comparison.js
@@ -0,0 +1,112 @@
+function getWritingMode(element, reference) {
+    var style = window.getComputedStyle(reference);
+    if (style.getPropertyValue("writing-mode") !== "horizontal-tb" ||
+        style.getPropertyValue("direction") !== "ltr")
+        throw "Reference should have writing mode horizontal-tb and ltr";
+
+    style = window.getComputedStyle(element);
+    var param =  {
+        rtl: style.getPropertyValue("direction") === "rtl",
+        mode: style.getPropertyValue("writing-mode")
+    };
+
+    return param;
+}
+
+function compareSize(element, reference, epsilon) {
+    var param = getWritingMode(element, reference);
+    var elementBox = element.getBoundingClientRect();
+    var referenceBox = reference.getBoundingClientRect();
+
+    switch(param.mode) {
+    case "horizontal-tb":
+        assert_approx_equals(elementBox.width, referenceBox.width, epsilon,
+                             "inline size");
+        assert_approx_equals(elementBox.height, referenceBox.height, epsilon,
+                             "block size");
+        break;
+    case "vertical-lr":
+    case "vertical-rl":
+        assert_approx_equals(elementBox.width, referenceBox.height, epsilon,
+                             "inline size");
+        assert_approx_equals(elementBox.height, referenceBox.width, epsilon,
+                             "block size");
+        break;
+    default:
+        throw "compareSize: Unrecognized writing-mode value";
+    }
+}
+
+function childrenHaveEmptyBoundingClientRects(element) {
+    Array.from(element.children).forEach(child => {
+        var childBox = child.getBoundingClientRect();
+        assert_true(childBox.left == 0 && childBox.right == 0 && childBox.top == 0 && childBox.bottom == 0);
+    })
+}
+
+function participateToParentLayout(child) {
+    var style = window.getComputedStyle(child);
+    return style.getPropertyValue("display") !== "none" &&
+        style.getPropertyValue("position") !== "absolute" &&
+        style.getPropertyValue("position") !== "fixed";
+}
+
+function childrenParticipatingToLayout(element) {
+    var children = [];
+    Array.from(element.children).forEach(child => {
+        if (participateToParentLayout(child))
+            children.push(child);
+    })
+    return children;
+}
+
+function compareLayout(element, reference, epsilon) {
+    // Compare sizes of elements and children.
+    var param = getWritingMode(element, reference);
+
+    compareSize(element, reference, epsilon);
+    var elementBox = element.getBoundingClientRect();
+    var referenceBox = reference.getBoundingClientRect();
+
+    var elementChildren = childrenParticipatingToLayout(element);
+    var referenceChildren = childrenParticipatingToLayout(reference);
+    if (elementChildren.length != referenceChildren.length)
+        throw "Reference should have the same number of children participating to layout."
+
+    for (var i = 0; i < elementChildren.length; i++) {
+        compareSize(elementChildren[i], referenceChildren[i], epsilon);
+
+        var childBox = elementChildren[i].getBoundingClientRect();
+        var referenceChildBox = referenceChildren[i].getBoundingClientRect();
+
+        switch(param.mode) {
+        case "horizontal-tb":
+            assert_approx_equals(param.rtl ?
+                                 elementBox.right - childBox.right :
+                                 childBox.left - elementBox.left,
+                                 referenceChildBox.left - referenceBox.left,
+                                 epsilon,
+                                 `inline position (child ${i})`);
+            assert_approx_equals(childBox.top - elementBox.top,
+                                 referenceChildBox.top - referenceBox.top,
+                                 epsilon,
+                                 `block position (child ${i})`);
+            break;
+        case "vertical-lr":
+        case "vertical-rl":
+            assert_approx_equals(param.rtl ?
+                                 elementBox.bottom - childBox.bottom :
+                                 childBox.top - elementBox.top,
+                                 referenceChildBox.left - referenceBox.left,
+                                 epsilon,
+                                 `inline position (child ${i})`);
+            assert_approx_equals(elementBox.right - childBox.right,
+                                 referenceChildBox.top - referenceBox.top,
+                                 epsilon,
+                                 `block position (child ${i})`);
+            break;
+        default:
+            throw "compareLayout: Unrecognized writing-mode value";
+        }
+    }
+}