From 96ed242c6d64f02d206359d681b9f9995d5aa798 Mon Sep 17 00:00:00 2001
From: Nate Bosch <nbosch@google.com>
Date: Wed, 10 May 2023 00:24:08 +0000
Subject: [PATCH] Add error for empty groups

Closes #1961

After declaring a group check for declared tests, if there were none add
a synthetic test that fails with an error about the empty group.
---
 pkgs/test/CHANGELOG.md                        |  1 +
 pkgs/test_api/CHANGELOG.md                    |  1 +
 pkgs/test_api/lib/src/backend/declarer.dart   |  6 ++++++
 pkgs/test_api/test/backend/declarer_test.dart | 11 +++++++++++
 pkgs/test_core/CHANGELOG.md                   |  1 +
 5 files changed, 20 insertions(+)

diff --git a/pkgs/test/CHANGELOG.md b/pkgs/test/CHANGELOG.md
index 8c0254eca..5038c6fcf 100644
--- a/pkgs/test/CHANGELOG.md
+++ b/pkgs/test/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 1.24.3-wip
 
 * Fix compatibility with wasm number semantics.
+* Consider empty `group` to be test failures.
 
 ## 1.24.2
 
diff --git a/pkgs/test_api/CHANGELOG.md b/pkgs/test_api/CHANGELOG.md
index 4d79f0a59..972cd189e 100644
--- a/pkgs/test_api/CHANGELOG.md
+++ b/pkgs/test_api/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 0.5.3-wip
 
 * Fix compatibility with wasm number semantics.
+* Consider empty `group` to be test failures.
 
 ## 0.5.2
 
diff --git a/pkgs/test_api/lib/src/backend/declarer.dart b/pkgs/test_api/lib/src/backend/declarer.dart
index 7a37552c6..999e3be13 100644
--- a/pkgs/test_api/lib/src/backend/declarer.dart
+++ b/pkgs/test_api/lib/src/backend/declarer.dart
@@ -13,6 +13,7 @@ import 'group_entry.dart';
 import 'invoker.dart';
 import 'metadata.dart';
 import 'test.dart';
+import 'test_failure.dart';
 
 /// A class that manages the state of tests as they're declared.
 ///
@@ -327,6 +328,11 @@ class Declarer {
       }
       return entry;
     }).toList();
+    if (entries.isEmpty) {
+      entries.add(LocalTest(_name ?? 'Empty group', _metadata, () {
+        throw TestFailure('No tests declared in group');
+      }));
+    }
 
     return Group(_name ?? '', entries,
         metadata: _metadata,
diff --git a/pkgs/test_api/test/backend/declarer_test.dart b/pkgs/test_api/test/backend/declarer_test.dart
index 0fe848a05..23e736d89 100644
--- a/pkgs/test_api/test/backend/declarer_test.dart
+++ b/pkgs/test_api/test/backend/declarer_test.dart
@@ -410,6 +410,17 @@ void main() {
       });
     });
 
+    test('disallows empty groups', () async {
+      var entries = declare(() {
+        group('group', () {});
+      });
+
+      expect(entries, hasLength(1));
+      var testGroup = entries.single as Group;
+      expect(testGroup.entries, hasLength(1));
+      await _runTest(testGroup.entries.single as Test, shouldFail: true);
+    });
+
     group('.setUp()', () {
       test('is scoped to the group', () async {
         var setUpRun = false;
diff --git a/pkgs/test_core/CHANGELOG.md b/pkgs/test_core/CHANGELOG.md
index 2f6be0845..bc456b2d0 100644
--- a/pkgs/test_core/CHANGELOG.md
+++ b/pkgs/test_core/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 0.5.3-wip
 
 * Fix compatibility with wasm number semantics.
+* Consider empty `group` to be test failures.
 
 ## 0.5.2