1 files changed, 70 insertions, 0 deletions
diff --git a/devtools/client/inspector/fonts/test/browser_fontinspector_edit-previews.js b/devtools/client/inspector/fonts/test/browser_fontinspector_edit-previews.js
new file mode 100644
index 0000000000..b29be4ca3f
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+++ b/devtools/client/inspector/fonts/test/browser_fontinspector_edit-previews.js
@@ -0,0 +1,70 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test that previews change when the preview text changes. It doesn't check the
+// exact preview images because they are drawn on a canvas causing them to vary
+// between systems, platforms and software versions.
+
+const TEST_URI = URL_ROOT + "doc_browser_fontinspector.html";
+
+add_task(async function () {
+  const { view, inspector } = await openFontInspectorForURL(TEST_URI);
+  const viewDoc = view.document;
+  await selectNode("div", inspector);
+  await expandFontsAccordion(viewDoc);
+
+  const previews = viewDoc.querySelectorAll("#font-container .font-preview");
+  const initialPreviews = [...previews].map(p => p.src);
+
+  info("Typing 'Abc' to check that the reference previews are correct.");
+  await updatePreviewText(view, "Abc");
+  checkPreviewImages(viewDoc, initialPreviews, true);
+
+  info("Typing something else to the preview box.");
+  await updatePreviewText(view, "The quick brown");
+  checkPreviewImages(viewDoc, initialPreviews, false);
+
+  info("Blanking the input to restore default previews.");
+  await updatePreviewText(view, "");
+  checkPreviewImages(viewDoc, initialPreviews, true);
+});
+
+/**
+ * Compares the previous preview image URIs to the current URIs.
+ *
+ * @param {Document} viewDoc
+ *        The FontInspector document.
+ * @param {Array[String]} originalURIs
+ *        An array of URIs to compare with the current URIs.
+ * @param {Boolean} assertIdentical
+ *        If true, this method asserts that the previous and current URIs are
+ *        identical. If false, this method asserts that the previous and current
+ *        URI's are different.
+ */
+function checkPreviewImages(viewDoc, originalURIs, assertIdentical) {
+  const previews = viewDoc.querySelectorAll("#font-container .font-preview");
+  const newURIs = [...previews].map(p => p.src);
+
+  is(
+    newURIs.length,
+    originalURIs.length,
+    "The number of previews has not changed."
+  );
+
+  for (let i = 0; i < newURIs.length; ++i) {
+    if (assertIdentical) {
+      is(
+        newURIs[i],
+        originalURIs[i],
+        `The preview image at index ${i} has stayed the same.`
+      );
+    } else {
+      isnot(
+        newURIs[i],
+        originalURIs[i],
+        `The preview image at index ${i} has changed.`
+      );
+    }
+  }
+}