diff -r 000000000000 -r 6474c204b198 browser/devtools/shadereditor/test/browser_webgl-actor-test-08.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/shadereditor/test/browser_webgl-actor-test-08.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,37 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests that the rendering is updated when a varying variable is
+ * changed in one shader.
+ */
+
+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("= aVertexColor", "= vec3(0, 0, 1)");
+  let status = yield vertexShader.compile(newVertSource);
+  ok(!status,
+    "The new vertex shader source was compiled without errors.");
+
+  yield waitForFrame(debuggee);
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 128, y: 128 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+  yield ensurePixelIs(debuggee, { x: 511, y: 511 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+
+  let vertSource = yield vertexShader.getText();
+  let fragSource = yield fragmentShader.getText();
+  ok(vertSource.contains("vFragmentColor = vec3(0, 0, 1);"),
+    "The vertex shader source is correct after changing it.");
+  ok(fragSource.contains("gl_FragColor = vec4(vFragmentColor, 1.0);"),
+    "The fragment shader source is correct after changing the vertex shader.");
+
+  yield removeTab(target.tab);
+  finish();
+}