3 files changed, 86 insertions, 0 deletions
diff --git a/tests/fixtures/display-lifecycle.js b/tests/fixtures/display-lifecycle.js
new file mode 100644
index 0000000..2173c47
--- /dev/null
+++ b/tests/fixtures/display-lifecycle.js
@@ -0,0 +1,56 @@
+import assert from 'node:assert/strict';
+
+class Extension {}
+const Meta = {MonitorSwitchConfigType: {EXTERNAL: 2}};
+let callback;
+let requests = 0;
+let switchable = true;
+let builtinOn = true;
+const manager = {
+    has_builtin_panel: true,
+    connect(signal, handler) {
+        assert.equal(signal, 'monitors-changed');
+        callback = handler;
+        return 1;
+    },
+    disconnect(id) {
+        assert.equal(id, 1);
+        callback = null;
+    },
+    can_switch_config: () => switchable,
+    get_is_builtin_display_on: () => builtinOn,
+    switch_config(type) {
+        assert.equal(type, Meta.MonitorSwitchConfigType.EXTERNAL);
+        requests++;
+        builtinOn = false;
+    },
+};
+globalThis.global = {backend: {get_monitor_manager: () => manager}};
+
+// EXTENSION
+
+const extension = new ExternalDisplay();
+extension.enable();
+assert.equal(requests, 1);
+callback();
+assert.equal(requests, 1);
+
+// One connected display, or a closed lid, prevents switching.
+switchable = false;
+builtinOn = true;
+callback();
+assert.equal(requests, 1);
+switchable = true;
+callback();
+assert.equal(requests, 2);
+
+manager.has_builtin_panel = false;
+builtinOn = true;
+callback();
+assert.equal(requests, 2);
+extension.disable();
+assert.equal(callback, null);
+manager.has_builtin_panel = true;
+extension.enable();
+assert.equal(requests, 3);
+extension.disable();
diff --git a/tests/test_canonical.py b/tests/test_canonical.py
index 848bf6c..fb0bff9 100644
--- a/tests/test_canonical.py
+++ b/tests/test_canonical.py
@@ -183,6 +183,7 @@ class RoleTests(unittest.TestCase):
             ".config/ghostty/config",
             ".local/bin/rqr",
             ".local/share/gnome-shell/extensions/corporate-panel@dotfiles/extension.js",
+            ".local/share/gnome-shell/extensions/external-display@dotfiles/extension.js",
         ]:
             self.assertIn(required, files)
         for path in files:
@@ -281,6 +282,7 @@ class RoleTests(unittest.TestCase):
             self.assertNotIn(".config/autostart/dotfiles-", files)
             self.assertNotIn("gpg-agent.service.d/canonical.conf", files)
             self.assertNotIn("corporate-panel@dotfiles", files)
+            self.assertNotIn("external-display@dotfiles", files)
 
 
 if __name__ == "__main__":
diff --git a/tests/test_canonical_displays.py b/tests/test_canonical_displays.py
new file mode 100644
index 0000000..627e3a0
--- /dev/null
+++ b/tests/test_canonical_displays.py
@@ -0,0 +1,28 @@
+import json
+import subprocess
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+EXTENSION = ROOT / "dot_local/share/gnome-shell/extensions/external-display@dotfiles"
+
+
+class DisplayTests(unittest.TestCase):
+    def test_metadata(self):
+        metadata = json.loads((EXTENSION / "metadata.json").read_text())
+        self.assertEqual(metadata["uuid"], "external-display@dotfiles")
+        self.assertIn("50", metadata["shell-version"])
+
+    def test_connection_changes_and_lifecycle(self):
+        code = "\n".join(
+            line
+            for line in (EXTENSION / "extension.js").read_text().splitlines()
+            if not line.startswith("import ")
+        ).replace("export default class", "class")
+        harness = (ROOT / "tests/fixtures/display-lifecycle.js").read_text()
+        subprocess.run(
+            ["node", "--input-type=module"],
+            input=harness.replace("// EXTENSION", code),
+            text=True,
+            check=True,
+        )