Fix bug with version parsing (flutter#3473)

Author: kenzieschmoll

.github/workflows/build.yaml

@@ -17,7 +17,7 @@ on:
 # track the latest Flutter dev release. Dev releases come out ~weekly;
 # the versions can be viewed at https://github.com/flutter/flutter/tags.
 env:
-  CHANNEL: 2.6.0-11.0.pre
+  CHANNEL: 2.7.0-3.0.pre
 
 jobs:
 

case_study/platform_channel/lib/channel_demo.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:flutter/widgets.dart';
 
 class ChannelDemo extends StatefulWidget {
   @override

flutter-version.txt

@@ -1 +1 @@
-2.6.0-11.0.pre
+2.7.0-3.0.pre

packages/devtools_app/lib/src/version.dart

@@ -88,11 +88,18 @@ class FlutterVersion extends SemanticVersion {
 
     // Example Dart version string: "2.15.0 (build 2.15.0-178.1.beta)"
     const prefix = '(build ';
-    final startIndex = versionString.indexOf(prefix) + prefix.length;
-    final rawVersion = versionString.substring(
-      startIndex,
-      versionString.length - 1,
-    );
+    final indexOfPrefix = versionString.indexOf(prefix);
+
+    String rawVersion;
+    if (indexOfPrefix != -1) {
+      final startIndex = indexOfPrefix + prefix.length;
+      rawVersion = versionString.substring(
+        startIndex,
+        versionString.length - 1,
+      );
+    } else {
+      rawVersion = versionString;
+    }
     return SemanticVersion.parse(rawVersion);
   }
 }

packages/devtools_app/test/version_test.dart

@@ -68,9 +68,39 @@ void main() {
       expect(flutterVersion.minor, equals(0));
       expect(flutterVersion.patch, equals(0));
     });
+
+    test('parses dart version correctly', () {
+      var flutterVersion = FlutterVersion.parse({
+        'frameworkVersion': '2.8.0',
+        'dartSdkVersion': '2.15.0',
+      });
+      expect(flutterVersion.dartSdkVersion.toString(), equals('2.15.0'));
+      flutterVersion = FlutterVersion.parse({
+        'frameworkVersion': '2.8.0',
+        'dartSdkVersion': '2.15.0 (build 2.15.0-178.1.beta)',
+      });
+      expect(flutterVersion.dartSdkVersion.toString(), equals('2.15.0-178.1'));
+    });
   });
 
   group('SemanticVersion', () {
+    test('parse', () {
+      expect(
+        SemanticVersion.parse(
+                '2.15.0-233.0.dev (dev) (Mon Oct 18 14:06:26 2021 -0700) on "ios_x64"')
+            .toString(),
+        equals('2.15.0-233.0'),
+      );
+      expect(
+        SemanticVersion.parse('2.15.0-178.1.beta').toString(),
+        equals('2.15.0-178.1'),
+      );
+      expect(
+        SemanticVersion.parse('2.6.0-12.0.pre.443').toString(),
+        equals('2.6.0-12.0'),
+      );
+    });
+
     test('isVersionSupported', () {
       final supportedVersion = SemanticVersion(major: 1, minor: 1, patch: 1);
       expect(