tests: Reach 100% coverage for keydown_util.

This commit pretty much just gets line coverage.

frontend_tests/node_tests/keydown_util.js

@@ -0,0 +1,26 @@
+set_global('$', global.make_zjquery());
+
+zrequire('keydown_util');
+
+run_test('test_early_returns', () => {
+    var stub = $.create('stub');
+    var opts = {
+        elem: stub,
+        handlers: {},
+    };
+
+    keydown_util.handle(opts);
+    var keydown_f = stub.keydown;
+
+    var e1 = {
+        which: 17, // not in keys
+    };
+
+    keydown_f(e1);
+
+    var e2 = {
+        which: 13, // no handler
+    };
+
+    keydown_f(e2);
+});

tools/test-js-with-node

@@ -43,6 +43,7 @@ enforce_fully_covered = {
     'static/js/fetch_status.js',
     'static/js/filter.js',
     'static/js/hash_util.js',
+    'static/js/keydown_util.js',
     'static/js/markdown.js',
     'static/js/message_store.js',
     'static/js/muting.js',