feat(shorebird_cli): add logcat to Adb (#836)

packages/shorebird_cli/lib/src/adb.dart

@@ -1,3 +1,6 @@
+import 'dart:async';
+import 'dart:io';
+
 import 'package:shorebird_cli/src/android_sdk.dart';
 import 'package:shorebird_cli/src/process.dart';
 
@@ -10,6 +13,13 @@ class Adb {
     return process.run(adbPath, command.split(' '));
   }
 
+  Future<Process> _stream(String command) async {
+    final adbPath = androidSdk.adbPath;
+    if (adbPath == null) throw Exception('Unable to locate adb.');
+
+    return process.start(adbPath, command.split(' '));
+  }
+
   /// Starts the app with the given [package] name.
   Future<void> startApp(String package) async {
     final result = await _exec('shell monkey -p $package 1');
@@ -17,4 +27,12 @@ class Adb {
       throw Exception('Unable to start app: ${result.stderr}');
     }
   }
+
+  Future<Process> logcat({String? filter}) async {
+    final logcat = await _stream('logcat');
+    if (filter == null) return logcat;
+    final grep = await process.start('grep', [filter]);
+    unawaited(logcat.stdout.pipe(grep.stdin));
+    return grep;
+  }
 }

packages/shorebird_cli/test/src/adb_test.dart

@@ -1,3 +1,5 @@
+import 'dart:io';
+
 import 'package:mocktail/mocktail.dart';
 import 'package:scoped/scoped.dart';
 import 'package:shorebird_cli/src/adb.dart';
@@ -9,6 +11,10 @@ class _MockAndroidSdk extends Mock implements AndroidSdk {}
 
 class _MockShorebirdProcess extends Mock implements ShorebirdProcess {}
 
+class _MockProcess extends Mock implements Process {}
+
+class _MockIOSink extends Mock implements IOSink {}
+
 void main() {
   group(Adb, () {
     const adbPath = '/path/to/adb';
@@ -27,6 +33,10 @@ void main() {
       );
     }
 
+    setUpAll(() {
+      registerFallbackValue(const Stream<List<int>>.empty());
+    });
+
     setUp(() {
       androidSdk = _MockAndroidSdk();
       process = _MockShorebirdProcess();
@@ -92,5 +102,59 @@ void main() {
         ).called(1);
       });
     });
+
+    group('logcat', () {
+      test('throws when unable to locate adb', () async {
+        when(() => androidSdk.adbPath).thenReturn(null);
+        await expectLater(
+          () => runWithOverrides(() => adb.logcat()),
+          throwsA(
+            isA<Exception>().having(
+              (e) => e.toString(),
+              'exception()',
+              contains('Unable to locate adb'),
+            ),
+          ),
+        );
+      });
+
+      test('returns correct process (unfiltered)', () async {
+        final Process logcatProcess = _MockProcess();
+        when(() => process.start(any(), any())).thenAnswer((invocation) async {
+          final executable = invocation.positionalArguments[0] as String;
+          if (executable == adbPath) return logcatProcess;
+          fail('Unexpected executable: $executable');
+        });
+        final result = await runWithOverrides(() => adb.logcat());
+        expect(result, equals(logcatProcess));
+        verify(() => process.start(adbPath, ['logcat'])).called(1);
+      });
+
+      test('returns correct process (filtered)', () async {
+        const filter = 'flutter';
+        final logcatProcess = _MockProcess();
+        final grepProcess = _MockProcess();
+        final grepStdin = _MockIOSink();
+        const logcatStdout = Stream<List<int>>.empty();
+
+        when(grepStdin.close).thenAnswer((_) async {});
+        when(() => grepStdin.addStream(any())).thenAnswer((_) async {});
+        when(() => grepProcess.stdin).thenReturn(grepStdin);
+        when(
+          () => logcatProcess.stdout,
+        ).thenAnswer((_) => logcatStdout);
+        when(() => process.start(any(), any())).thenAnswer((invocation) async {
+          final executable = invocation.positionalArguments[0] as String;
+          if (executable == adbPath) return logcatProcess;
+          if (executable == 'grep') return grepProcess;
+          fail('Unexpected executable: $executable');
+        });
+        final result = await runWithOverrides(() => adb.logcat(filter: filter));
+        expect(result, equals(grepProcess));
+        verify(() => process.start(adbPath, ['logcat'])).called(1);
+        verify(() => process.start('grep', [filter])).called(1);
+        verify(() => grepStdin.addStream(logcatStdout)).called(1);
+      });
+    });
   });
 }