node tests: Add make_stream helper to create streams in node tests.

With a bunch of comments by tabbott on some details to pay attention
to.

web/tests/example1.test.js

@@ -11,6 +11,7 @@ const {strict: assert} = require("assert");
 
 const {zrequire} = require("./lib/namespace");
 const {run_test} = require("./lib/test");
+const {make_stream} = require("./lib/test_stream");
 
 // We will use our special zrequire helper to import the
 // Zulip code. We use zrequire instead of require,
@@ -52,12 +53,14 @@ assert.ok(people.is_known_user_id(isaac.user_id));
 // some data at module scope. (You could also declare this inside
 // the test, if you prefer.)
 
-const denmark_stream = {
-    color: "blue",
+// We use make_stream to create a complete stream object with select
+// fields explicitly specified, and all other fields populated with
+// reasonable defaults.
+const denmark_stream = make_stream({
+    color: "a1a1a1",
     name: "Denmark",
-    stream_id: 101,
     subscribed: false,
-};
+});
 
 // We introduce the run_test helper, which mostly just causes
 // a line of output to go to the console. It does a little more than
@@ -68,6 +71,6 @@ run_test("verify stream_data persists stream color", () => {
     assert.equal(stream_data.get_sub_by_name("Denmark"), undefined);
     stream_data.add_sub(denmark_stream);
     const sub = stream_data.get_sub_by_name("Denmark");
-    assert.equal(sub.color, "blue");
+    assert.equal(sub.color, "a1a1a1");
 });
 // See example2.test.js in this directory.

web/tests/example2.test.js

@@ -4,6 +4,7 @@ const {strict: assert} = require("assert");
 
 const {zrequire} = require("./lib/namespace");
 const {run_test} = require("./lib/test");
+const {make_stream} = require("./lib/test_stream");
 
 // Hopefully the basic patterns for testing data-oriented modules
 // are starting to become apparent.  To reinforce that, we will present
@@ -28,12 +29,12 @@ const isaac = {
     full_name: "Isaac Newton",
 };
 
-const denmark_stream = {
+const denmark_stream = make_stream({
     color: "blue",
     name: "Denmark",
     stream_id: 101,
     subscribed: false,
-};
+});
 
 const messages = {
     isaac_to_denmark_stream: {

web/tests/example3.test.js

@@ -4,6 +4,7 @@ const {strict: assert} = require("assert");
 
 const {zrequire} = require("./lib/namespace");
 const {run_test} = require("./lib/test");
+const {make_stream} = require("./lib/test_stream");
 const {realm} = require("./lib/zpage_params");
 
 // In the Zulip app you can narrow your message stream by topic, by
@@ -21,12 +22,12 @@ const stream_data = zrequire("stream_data");
 // realm, since we want to test the "normal" codepath.
 realm.realm_is_zephyr_mirror_realm = false;
 
-const denmark_stream = {
+const denmark_stream = make_stream({
     color: "blue",
     name: "Denmark",
     stream_id: 101,
     subscribed: false,
-};
+});
 
 run_test("filter", () => {
     stream_data.clear_subscriptions();

web/tests/example7.test.js

@@ -4,6 +4,7 @@ const {strict: assert} = require("assert");
 
 const {mock_esm, set_global, zrequire} = require("./lib/namespace");
 const {run_test, noop} = require("./lib/test");
+const {make_stream} = require("./lib/test_stream");
 const $ = require("./lib/zjquery");
 
 /*
@@ -66,12 +67,12 @@ const stream_data = zrequire("stream_data");
 const unread = zrequire("unread");
 const unread_ops = zrequire("unread_ops");
 
-const denmark_stream = {
+const denmark_stream = make_stream({
     color: "blue",
     name: "Denmark",
     stream_id: 101,
     subscribed: false,
-};
+});
 
 run_test("unread_ops", ({override}) => {
     stream_data.clear_subscriptions();

web/tests/lib/test_stream.js

@@ -0,0 +1,54 @@
+"use strict";
+
+let last_issued_stream_id = 20000;
+
+const get_stream_id = () => {
+    last_issued_stream_id += 1 + Math.floor(Math.random() * 10);
+    return last_issued_stream_id;
+};
+
+exports.make_stream = (opts = {}) => {
+    // Since other fields are computed from these, we need to
+    // pull these out of opts early.
+    const stream_id = opts.stream_id ?? get_stream_id();
+    const name = opts.name ?? `stream-${stream_id}`;
+
+    const default_channel = {
+        audible_notifications: false,
+        /* BUG: This should always be a group ID. But it's annoying to
+         * fix without assuming groups exist in the data set. */
+        can_remove_subscribers_group: 0,
+        color: "abcd12",
+        /* This is rarely going to be the case, but a valid possibility. */
+        creator_id: null,
+        date_created: Date.now(),
+        description: `Description of ${name}`,
+        desktop_notifications: false,
+        email_address: "channel-email-address@example.com",
+        email_notifications: false,
+        /* This will rarely be the case, but is a valid possibility*/
+        first_message_id: null,
+        history_public_to_subscribers: true,
+        invite_only: false,
+        is_announcement_only: false,
+        is_muted: false,
+        is_web_public: false,
+        message_retention_days: null,
+        name,
+        newly_subscribed: false,
+        pin_to_top: false,
+        previously_subscribed: false,
+        push_notifications: false,
+        render_subscribers: false,
+        rendered_description: `<p>Description of ${name}</p>`,
+        stream_id,
+        /* STREAM_POST_POLICY_EVERYONE */
+        stream_post_policy: 1,
+        stream_weekly_traffic: 0,
+        /* Most tests want to work with a channel the current user is subscribed to. */
+        subscribed: true,
+        wildcard_mentions_notify: false,
+    };
+
+    return {...default_channel, ...opts};
+};