3 files changed, 91 insertions, 0 deletions
diff --git a/devtools/client/framework/test/xpcshell/.eslintrc.js b/devtools/client/framework/test/xpcshell/.eslintrc.js
new file mode 100644
index 0000000000..7f6b62a9e5
--- /dev/null
+++ b/devtools/client/framework/test/xpcshell/.eslintrc.js
@@ -0,0 +1,6 @@
+"use strict";
+
+module.exports = {
+  // Extend from the shared list of defined globals for mochitests.
+  extends: "../../../../.eslintrc.xpcshell.js",
+};
diff --git a/devtools/client/framework/test/xpcshell/test_tabs_absolute_order.js b/devtools/client/framework/test/xpcshell/test_tabs_absolute_order.js
new file mode 100644
index 0000000000..9f2220ed81
--- /dev/null
+++ b/devtools/client/framework/test/xpcshell/test_tabs_absolute_order.js
@@ -0,0 +1,79 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm");
+
+const TEST_DATA = [
+  {
+    description: "Test for no order in preference",
+    preferenceOrder: [],
+    currentTabsOrder: ["T1", "T2", "T3", "T4", "T5"],
+    dragTarget: "T1",
+    expectedOrder: ["T1", "T2", "T3", "T4", "T5"],
+  },
+  {
+    description: "Test for drag a tab to left with hidden tab",
+    preferenceOrder: ["T1", "T2", "T3", "E1", "T4", "T5"],
+    currentTabsOrder: ["T1", "T2", "T4", "T3", "T5"],
+    dragTarget: "T4",
+    expectedOrder: ["T1", "T2", "T4", "T3", "E1", "T5"],
+  },
+  {
+    description: "Test for drag a tab to right with hidden tab",
+    preferenceOrder: ["T1", "T2", "T3", "E1", "T4", "T5"],
+    currentTabsOrder: ["T1", "T3", "T4", "T2", "T5"],
+    dragTarget: "T2",
+    expectedOrder: ["T1", "T3", "E1", "T4", "T2", "T5"],
+  },
+  {
+    description:
+      "Test for drag a tab to left end in case hidden tab was left end",
+    preferenceOrder: ["E1", "T1", "T2", "T3", "T4", "T5"],
+    currentTabsOrder: ["T4", "T1", "T2", "T3", "T5"],
+    dragTarget: "T4",
+    expectedOrder: ["E1", "T4", "T1", "T2", "T3", "T5"],
+  },
+  {
+    description:
+      "Test for drag a tab to right end in case hidden tab was right end",
+    preferenceOrder: ["T1", "T2", "T3", "T4", "T5", "E1"],
+    currentTabsOrder: ["T2", "T3", "T4", "T5", "T1"],
+    dragTarget: "T1",
+    expectedOrder: ["T2", "T3", "T4", "T5", "E1", "T1"],
+  },
+  {
+    description: "Test for multiple hidden tabs",
+    preferenceOrder: ["T1", "T2", "E1", "E2", "E3", "E4"],
+    currentTabsOrder: ["T2", "T1"],
+    dragTarget: "T1",
+    expectedOrder: ["T2", "E1", "E2", "E3", "E4", "T1"],
+  },
+];
+
+function run_test() {
+  const {
+    toAbsoluteOrder,
+  } = require("devtools/client/framework/toolbox-tabs-order-manager");
+
+  for (const {
+    description,
+    preferenceOrder,
+    currentTabsOrder,
+    dragTarget,
+    expectedOrder,
+  } of TEST_DATA) {
+    info(description);
+    const resultOrder = toAbsoluteOrder(
+      preferenceOrder,
+      currentTabsOrder,
+      dragTarget
+    );
+    equal(
+      resultOrder.join(","),
+      expectedOrder.join(","),
+      "Result should be correct"
+    );
+  }
+}
diff --git a/devtools/client/framework/test/xpcshell/xpcshell.ini b/devtools/client/framework/test/xpcshell/xpcshell.ini
new file mode 100644
index 0000000000..6f68037a48
--- /dev/null
+++ b/devtools/client/framework/test/xpcshell/xpcshell.ini
@@ -0,0 +1,6 @@
+[DEFAULT]
+tags = devtools
+firefox-appdir = browser
+skip-if = toolkit == 'android'
+
+[test_tabs_absolute_order.js]