[tools] Make sure assemble has a pubspec as cwd (flutter#184067)

Bug:

* flutter#169475

Forces `flutter assemble` to have a cwd with a pubspec. This will give
errors earlier than the NPE in the linked bug.

Author: dcharkes

packages/flutter_tools/lib/src/commands/assemble.dart

@@ -97,6 +97,7 @@ class AssembleCommand extends FlutterCommand {
   AssembleCommand({bool verboseHelp = false, required BuildSystem buildSystem})
     : _verboseHelp = verboseHelp,
       _buildSystem = buildSystem {
+    requiresPubspecYaml();
     argParser.addMultiOption(
       'define',
       abbr: 'd',

packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart

@@ -28,9 +28,13 @@ void main() {
   final StackTrace stackTrace = StackTrace.current;
   late FakeAnalytics fakeAnalytics;
 
+  late MemoryFileSystem fileSystem;
+
   setUp(() {
+    fileSystem = MemoryFileSystem.test();
+    fileSystem.file('pubspec.yaml').createSync();
     fakeAnalytics = getInitializedFakeAnalyticsInstance(
-      fs: MemoryFileSystem.test(),
+      fs: fileSystem,
       fakeFlutterVersion: FakeFlutterVersion(),
     );
   });
@@ -51,7 +55,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -80,7 +84,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -109,7 +113,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -138,7 +142,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -160,7 +164,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
       FeatureFlags: () => TestFeatureFlags(isMacOSEnabled: true),
     },
@@ -192,7 +196,7 @@ void main() {
     overrides: <Type, Generator>{
       Analytics: () => fakeAnalytics,
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -224,7 +228,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
       FeatureFlags: () => TestFeatureFlags(isMacOSEnabled: true),
       Analytics: () => fakeAnalytics,
@@ -245,7 +249,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -269,7 +273,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -298,7 +302,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -314,7 +318,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -344,7 +348,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -386,7 +390,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -416,7 +420,7 @@ void main() {
         localEngineHost: 'out/host_release',
       ),
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -489,7 +493,7 @@ void main() {
     },
     overrides: <Type, Generator>{
       Cache: () => Cache.test(processManager: FakeProcessManager.any()),
-      FileSystem: () => MemoryFileSystem.test(),
+      FileSystem: () => fileSystem,
       ProcessManager: () => FakeProcessManager.any(),
     },
   );
@@ -545,6 +549,24 @@ void main() {
     await commandRunner.run(['--help' /* -- verbose omitted (verboseHelp: true) is set above */]);
     expect(testLogger.statusText, contains('assemble'));
   });
+
+  testUsingContext(
+    'flutter assemble fails if pubspec.yaml is missing',
+    () async {
+      final CommandRunner<void> commandRunner = createTestCommandRunner(
+        AssembleCommand(buildSystem: TestBuildSystem.error(null)),
+      );
+
+      await expectLater(
+        commandRunner.run(<String>['assemble', '-o Output', 'debug_macos_bundle_flutter_assets']),
+        throwsToolExit(message: 'No pubspec.yaml file found'),
+      );
+    },
+    overrides: <Type, Generator>{
+      FileSystem: () => MemoryFileSystem.test(),
+      ProcessManager: () => FakeProcessManager.any(),
+    },
+  );
 }
 
 final class _StubCommand extends FlutterCommand {