1 files changed, 127 insertions, 0 deletions
diff --git a/testing/mochitest/tests/SimpleTest/WindowSnapshot.js b/testing/mochitest/tests/SimpleTest/WindowSnapshot.js
new file mode 100644
index 0000000000..62f1062b36
--- /dev/null
+++ b/testing/mochitest/tests/SimpleTest/WindowSnapshot.js
@@ -0,0 +1,127 @@
+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: " +
+        s1.width +
+        "x" +
+        s1.height +
+        " vs. " +
+        s2.width +
+        "x" +
+        s2.height
+    );
+    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) {
+    let status = "TEST-UNEXPECTED-FAIL";
+    if (usesFailurePatterns() && recordIfMatchesFailurePattern(s1name)) {
+      status = "TEST-KNOWN-FAIL";
+    }
+    // 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 " +
+      status +
+      " | " +
+      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";
+    }
+    (info || 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);
+}