test: Use stream ID in default name and description in eg.stream

In particular this means that repeated calls `eg.stream()` with
no arguments will get distinct names, as well as IDs, so that they
can all be added to the same store without collision.

Then also simplify away the various places where a test was passing
a stream name when the only thing about the name that mattered to
the test was being distinct from other names (or when nothing about
the name mattered to the test at all).

test/example_data.dart

@@ -175,11 +175,14 @@ ZulipStream stream({
   int? canRemoveSubscribersGroup,
   int? streamWeeklyTraffic,
 }) {
+  var effectiveStreamId = streamId ?? _nextStreamId();
+  var effectiveName = name ?? 'stream $effectiveStreamId';
+  var effectiveDescription = description ?? 'Description of $effectiveName';
   return ZulipStream(
-    streamId: streamId ?? _nextStreamId(),
-    name: name ?? 'A stream', // TODO generate example names
-    description: description ?? 'A description', // TODO generate example descriptions
-    renderedDescription: renderedDescription ?? '<p>A description</p>', // TODO generate random
+    streamId: effectiveStreamId,
+    name: effectiveName,
+    description: effectiveDescription,
+    renderedDescription: renderedDescription ?? '<p>$effectiveDescription</p>',
     dateCreated: dateCreated ?? 1686774898,
     firstMessageId: firstMessageId,
     inviteOnly: inviteOnly ?? false,

test/model/channel_test.dart

@@ -34,17 +34,17 @@ void main() {
     }
 
     test('initial', () {
-      final stream1 = eg.stream(streamId: 1, name: 'stream 1');
-      final stream2 = eg.stream(streamId: 2, name: 'stream 2');
+      final stream1 = eg.stream();
+      final stream2 = eg.stream();
       checkUnified(eg.store(initialSnapshot: eg.initialSnapshot(
         streams: [stream1, stream2],
         subscriptions: [eg.subscription(stream1)],
       )));
     });
 
     test('added by events', () async {
-      final stream1 = eg.stream(streamId: 1, name: 'stream 1');
-      final stream2 = eg.stream(streamId: 2, name: 'stream 2');
+      final stream1 = eg.stream();
+      final stream2 = eg.stream();
       final store = eg.store();
       checkUnified(store);
 
@@ -106,8 +106,8 @@ void main() {
   });
 
   group('topic visibility', () {
-    final stream1 = eg.stream(streamId: 1, name: 'stream 1');
-    final stream2 = eg.stream(streamId: 2, name: 'stream 2');
+    final stream1 = eg.stream();
+    final stream2 = eg.stream();
 
     group('getter topicVisibilityPolicy', () {
       test('with nothing for stream', () {

test/model/message_list_test.dart

@@ -467,8 +467,8 @@ void main() {
   });
 
   group('messagesMoved', () {
-    final stream = eg.stream(streamId: 1, name: 'test stream');
-    final otherStream = eg.stream(streamId: 2, name: 'other stream');
+    final stream = eg.stream();
+    final otherStream = eg.stream();
 
     void checkHasMessages(Iterable<Message> messages) {
       check(model.messages.map((e) => e.id)).deepEquals(messages.map((e) => e.id));
@@ -945,8 +945,8 @@ void main() {
 
   group('stream/topic muting', () {
     test('in CombinedFeedNarrow', () async {
-      final stream1 = eg.stream(streamId: 1, name: 'stream 1');
-      final stream2 = eg.stream(streamId: 2, name: 'stream 2');
+      final stream1 = eg.stream();
+      final stream2 = eg.stream();
       await prepare(narrow: const CombinedFeedNarrow());
       await store.addStreams([stream1, stream2]);
       await store.addSubscription(eg.subscription(stream1));
@@ -1008,7 +1008,7 @@ void main() {
     });
 
     test('in StreamNarrow', () async {
-      final stream = eg.stream(streamId: 1, name: 'stream 1');
+      final stream = eg.stream();
       await prepare(narrow: StreamNarrow(stream.streamId));
       await store.addStream(stream);
       await store.addSubscription(eg.subscription(stream, isMuted: true));
@@ -1055,7 +1055,7 @@ void main() {
     });
 
     test('in TopicNarrow', () async {
-      final stream = eg.stream(streamId: 1, name: 'stream 1');
+      final stream = eg.stream();
       await prepare(narrow: TopicNarrow(stream.streamId, 'A'));
       await store.addStream(stream);
       await store.addSubscription(eg.subscription(stream, isMuted: true));

test/model/unreads_test.dart

@@ -153,9 +153,9 @@ void main() {
 
   group('count helpers', () {
     test('countInCombinedFeedNarrow', () async {
-      final stream1 = eg.stream(streamId: 1, name: 'stream 1');
-      final stream2 = eg.stream(streamId: 2, name: 'stream 2');
-      final stream3 = eg.stream(streamId: 3, name: 'stream 3');
+      final stream1 = eg.stream();
+      final stream2 = eg.stream();
+      final stream3 = eg.stream();
       prepare();
       await channelStore.addStreams([stream1, stream2, stream3]);
       await channelStore.addSubscription(eg.subscription(stream1));