snapshot of https://github.com/zulip/zulip.git @ 48c69911c7dd4e03b20552eb3bd77ad8151c1357 (2026-09-15)

web/tests/example3.test.cjs

@@ -0,0 +1,93 @@
+"use strict";
+
+const assert = require("node:assert/strict");
+
+const {make_realm} = require("./lib/example_realm.cjs");
+const {make_stream} = require("./lib/example_stream.cjs");
+const {make_message_list} = require("./lib/message_list.cjs");
+const {zrequire} = require("./lib/namespace.cjs");
+const {run_test} = require("./lib/test.cjs");
+
+// In the Zulip app you can narrow your message stream by topic, by
+// sender, by direct message recipient, by search keywords, etc.
+// We will discuss narrows more broadly, but first let's test out a
+// core piece of code that makes things work.
+
+const {Filter} = zrequire("../src/filter");
+const {set_realm} = zrequire("state_data");
+const stream_data = zrequire("stream_data");
+
+set_realm(make_realm());
+
+const denmark_stream = make_stream({
+    color: "blue",
+    name: "Denmark",
+    stream_id: 101,
+    subscribed: false,
+});
+
+run_test("filter", () => {
+    stream_data.clear_subscriptions();
+    stream_data.add_sub_for_tests(denmark_stream);
+
+    const filter_terms = [
+        {operator: "stream", operand: denmark_stream.stream_id.toString()},
+        {operator: "topic", operand: "copenhagen"},
+    ];
+
+    const filter = new Filter(filter_terms);
+
+    const predicate = filter.predicate();
+
+    // We don't need full-fledged messages to test the gist of
+    // our filter.  If there are details that are distracting from
+    // your test, you should not feel guilty about removing them.
+    assert.equal(predicate({type: "personal"}), false);
+
+    assert.equal(
+        predicate({
+            type: "stream",
+            stream_id: denmark_stream.stream_id,
+            topic: "does not match filter",
+        }),
+        false,
+    );
+
+    assert.equal(
+        predicate({
+            type: "stream",
+            stream_id: denmark_stream.stream_id,
+            topic: "copenhagen",
+        }),
+        true,
+    );
+});
+
+// We have a "narrow" abstraction that sits roughly on top of the
+// "filter" abstraction.  If you are in a narrow, we track the
+// state with the narrow_state module.
+
+const narrow_state = zrequire("narrow_state");
+const message_lists = zrequire("message_lists");
+
+run_test("narrow_state", () => {
+    stream_data.clear_subscriptions();
+    stream_data.add_sub_for_tests(denmark_stream);
+    message_lists.set_current(undefined);
+
+    // As we often do, first make assertions about the starting
+    // state:
+
+    assert.equal(narrow_state.stream_name(), undefined);
+
+    // Now set up a Filter object.
+    const filter_terms = [
+        {operator: "stream", operand: denmark_stream.stream_id.toString()},
+        {operator: "topic", operand: "copenhagen"},
+    ];
+
+    // And here is where we actually change state.
+    message_lists.set_current(make_message_list(filter_terms));
+    assert.equal(narrow_state.stream_name(), "Denmark");
+    assert.equal(narrow_state.topic(), "copenhagen");
+});