1 files changed, 92 insertions, 0 deletions
diff --git a/testing/mochitest/tests/SimpleTest/WindowSnapshot.js b/testing/mochitest/tests/SimpleTest/WindowSnapshot.js
new file mode 100644
index 000000000..c4ced41dd
--- /dev/null
+++ b/testing/mochitest/tests/SimpleTest/WindowSnapshot.js
@@ -0,0 +1,92 @@
+var gWindowUtils;
+
+try {
+  gWindowUtils = SpecialPowers.getDOMWindowUtils(window);
+  if (gWindowUtils && !gWindowUtils.compareCanvases)
+    gWindowUtils = null;
+} catch (e) {
+  gWindowUtils = null;
+}
+
+function snapshotWindow(win, withCaret) {
+  return SpecialPowers.snapshotWindow(win, withCaret);
+}
+
+function snapshotRect(win, rect) {
+  return SpecialPowers.snapshotRect(win, rect);
+}
+
+// If the two snapshots don't compare as expected (true for equal, false for
+// unequal), returns their serializations as data URIs.  In all cases, returns
+// whether the comparison was as expected.
+function compareSnapshots(s1, s2, expectEqual, fuzz) {
+  if (s1.width != s2.width || s1.height != s2.height) {
+    ok(false, "Snapshot canvases are not the same size - comparing them makes no sense");
+    return [false];
+  }
+  var passed = false;
+  var numDifferentPixels;
+  var maxDifference = { value: undefined };
+  if (gWindowUtils) {
+    var equal;
+    try {
+      numDifferentPixels = gWindowUtils.compareCanvases(s1, s2, maxDifference);
+      if (!fuzz) {
+        equal = (numDifferentPixels == 0);
+      } else {
+        equal = (numDifferentPixels <= fuzz.numDifferentPixels &&
+                 maxDifference.value <= fuzz.maxDifference);
+      }
+      passed = (equal == expectEqual);
+    } catch (e) {
+      ok(false, "Exception thrown from compareCanvases: " + e);
+    }
+  }
+
+  var s1DataURI, s2DataURI;
+  if (!passed) {
+    s1DataURI = s1.toDataURL();
+    s2DataURI = s2.toDataURL();
+
+    if (!gWindowUtils) {
+      passed = ((s1DataURI == s2DataURI) == expectEqual);
+    }
+  }
+
+  return [passed, s1DataURI, s2DataURI, numDifferentPixels, maxDifference.value];
+}
+
+function assertSnapshots(s1, s2, expectEqual, fuzz, s1name, s2name) {
+  var [passed, s1DataURI, s2DataURI, numDifferentPixels, maxDifference] =
+    compareSnapshots(s1, s2, expectEqual, fuzz);
+  var sym = expectEqual ? "==" : "!=";
+  ok(passed, "reftest comparison: " + sym + " " + s1name + " " + s2name);
+  if (!passed) {
+    // The language / format in this message should match the failure messages
+    // displayed by reftest.js's "RecordResult()" method so that log output
+    // can be parsed by reftest-analyzer.xhtml
+    var report = "REFTEST TEST-UNEXPECTED-FAIL | " + s1name +
+                 " | image comparison (" + sym + "), max difference: " +
+                 maxDifference + ", number of differing pixels: " +
+                 numDifferentPixels + "\n";
+    if (expectEqual) {
+      report += "REFTEST   IMAGE 1 (TEST): " + s1DataURI + "\n";
+      report += "REFTEST   IMAGE 2 (REFERENCE): " + s2DataURI + "\n";
+    } else {
+      report += "REFTEST   IMAGE: " + s1DataURI + "\n";
+    }
+    dump(report);
+  }
+  return passed;
+}
+
+function assertWindowPureColor(win, color) {
+  const snapshot = SpecialPowers.snapshotRect(win);
+  const canvas = document.createElement("canvas");
+  canvas.width = snapshot.width;
+  canvas.height = snapshot.height;
+  const context = canvas.getContext("2d");
+  context.fillStyle = color;
+  context.fillRect(0, 0, canvas.width, canvas.height);
+  assertSnapshots(snapshot, canvas, true, null, "snapshot", color);
+}