diff -r 000000000000 -r 6474c204b198 browser/devtools/shadereditor/test/browser_webgl-actor-test-09.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/shadereditor/test/browser_webgl-actor-test-09.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests that errors are properly handled when trying to compile a
+ * defective shader source.
+ */
+
+function ifWebGLSupported() {
+  let [target, debuggee, front] = yield initBackend(SIMPLE_CANVAS_URL);
+  front.setup({ reload: true });
+
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
+
+  let oldVertSource = yield vertexShader.getText();
+  let newVertSource = oldVertSource.replace("vec4", "vec3");
+
+  try {
+    yield vertexShader.compile(newVertSource);
+    ok(false, "Vertex shader was compiled with a defective source!");
+  } catch (error) {
+    ok(error,
+      "The new vertex shader source was compiled with errors.");
+    is(error.compile, "",
+      "The compilation status should be empty.");
+    isnot(error.link, "",
+      "The linkage status should not be empty.");
+    is(error.link.split("ERROR").length - 1, 2,
+      "The linkage status contains two errors.");
+    ok(error.link.contains("ERROR: 0:8: 'constructor'"),
+      "A constructor error is contained in the linkage status.");
+    ok(error.link.contains("ERROR: 0:8: 'assign'"),
+      "An assignment error is contained in the linkage status.");
+  }
+
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  ok(true, "The shader was reverted to the old source.");
+
+  let vertSource = yield vertexShader.getText();
+  ok(vertSource.contains("vec4(aVertexPosition, 1.0);"),
+    "The previous correct vertex shader source was preserved.");
+
+  let oldFragSource = yield fragmentShader.getText();
+  let newFragSource = oldFragSource.replace("vec3", "vec4");
+
+  try {
+    yield fragmentShader.compile(newFragSource);
+    ok(false, "Fragment shader was compiled with a defective source!");
+  } catch (error) {
+    ok(error,
+      "The new fragment shader source was compiled with errors.");
+    is(error.compile, "",
+      "The compilation status should be empty.");
+    isnot(error.link, "",
+      "The linkage status should not be empty.");
+    is(error.link.split("ERROR").length - 1, 1,
+      "The linkage status contains one error.");
+    ok(error.link.contains("ERROR: 0:6: 'constructor'"),
+      "A constructor error is contained in the linkage status.");
+  }
+
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  ok(true, "The shader was reverted to the old source.");
+
+  let fragSource = yield fragmentShader.getText();
+  ok(fragSource.contains("vec3 vFragmentColor;"),
+    "The previous correct fragment shader source was preserved.");
+
+  yield programActor.highlight([0, 1, 0, 1]);
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  ok(true, "Highlighting worked after setting a defective fragment source.");
+
+  yield programActor.unhighlight();
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  ok(true, "Unhighlighting worked after setting a defective vertex source.");
+
+  yield removeTab(target.tab);
+  finish();
+}