1 files changed, 40 insertions, 0 deletions
diff --git a/devtools/client/inspector/rules/test/browser_rules_edit-variable-add.js b/devtools/client/inspector/rules/test/browser_rules_edit-variable-add.js
new file mode 100644
index 0000000000..3c4c9a25a4
--- /dev/null
+++ b/devtools/client/inspector/rules/test/browser_rules_edit-variable-add.js
@@ -0,0 +1,40 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test adding a CSS variable.
+
+const TEST_URI = `
+  <style type='text/css'>
+    div {
+      color: var(--color);
+    }
+  </style>
+  <div></div>
+`;
+
+add_task(async function () {
+  await addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
+  const { inspector, view } = await openRuleView();
+  await selectNode("div", inspector);
+
+  info("Check the initial state of --color which refers to an unset variable");
+  checkCSSVariableOutput(
+    view,
+    "div",
+    "color",
+    "ruleview-unmatched-variable",
+    "--color is not set"
+  );
+
+  info("Add the --color CSS variable");
+  await addProperty(view, 0, "--color", "lime");
+  checkCSSVariableOutput(
+    view,
+    "div",
+    "color",
+    "ruleview-variable",
+    "--color = lime"
+  );
+});