1 files changed, 27 insertions, 0 deletions
diff --git a/devtools/client/responsive/test/xpcshell/test_change_pixel_ratio.js b/devtools/client/responsive/test/xpcshell/test_change_pixel_ratio.js
new file mode 100644
index 0000000000..d462cf39cc
--- /dev/null
+++ b/devtools/client/responsive/test/xpcshell/test_change_pixel_ratio.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test changing the viewport pixel ratio.
+
+const {
+  addViewport,
+  changePixelRatio,
+} = require("resource://devtools/client/responsive/actions/viewports.js");
+const NEW_PIXEL_RATIO = 5.5;
+
+add_task(async function () {
+  const store = Store();
+  const { getState, dispatch } = store;
+
+  dispatch(addViewport());
+  dispatch(changePixelRatio(0, NEW_PIXEL_RATIO));
+
+  const viewport = getState().viewports[0];
+  equal(
+    viewport.pixelRatio,
+    NEW_PIXEL_RATIO,
+    `Viewport's pixel ratio changed to ${NEW_PIXEL_RATIO}`
+  );
+});