Allow integration test helpers to work on substrings instead of whole strings (#160437)

The integration test framework that waits for transitions and
(optionally) takes actions on transitions allows to match patterns.

If one uses a RegExp pattern than the framework only checks whether a
line contains the given RegExp pattern.

If one uses a String pattern it matches it exactly.

=> We add a `Barrier.contains()` and `Multiple.contains()` that allow
matching a line with if it contains the String (just like in RegExp)

=> This makes tests simpler as they don't have to know about the exact
padding of progres bar etc. Those may be irrelevant for the purpose of
the integration test and only complicate it.

Author: mkustermann

packages/flutter_tools/test/integration.shard/isolated/native_assets_test.dart

@@ -72,7 +72,7 @@ void main() {
             <String>['run', '-d$device', '--$buildMode'],
             exampleDirectory.path,
             <Transition>[
-              Multiple(
+              Multiple.contains(
                 <Pattern>['Flutter run key commands.'],
                 handler: (String line) {
                   if (buildMode == 'debug') {
@@ -85,31 +85,31 @@ void main() {
                 },
               ),
               if (buildMode == 'debug') ...<Transition>[
-                Barrier('Performing hot reload...'.padRight(progressMessageWidth), logging: true),
+                Barrier.contains('Performing hot reload...', logging: true),
                 Multiple(
                   <Pattern>[RegExp('Reloaded .*')],
                   handler: (String line) {
                     // Do a hot restart, pushing a new complete dill file.
                     return 'R';
                   },
                 ),
-                Barrier('Performing hot restart...'.padRight(progressMessageWidth)),
+                Barrier.contains('Performing hot restart...'),
                 Multiple(
                   <Pattern>[RegExp('Restarted application .*')],
                   handler: (String line) {
                     // Do another hot reload, pushing a diff to the second dill file.
                     return 'r';
                   },
                 ),
-                Barrier('Performing hot reload...'.padRight(progressMessageWidth), logging: true),
+                Barrier.contains('Performing hot reload...', logging: true),
                 Multiple(
                   <Pattern>[RegExp('Reloaded .*')],
                   handler: (String line) {
                     return 'q';
                   },
                 ),
               ],
-              const Barrier('Application finished.'),
+              Barrier.contains('Application finished.'),
             ],
             logging: false,
           );

packages/flutter_tools/test/integration.shard/overall_experience_test.dart

@@ -56,7 +56,7 @@ void main() {
                 return 'q';
               },
             ),
-            const Barrier('Application finished.'),
+            Barrier('Application finished.'),
           ],
         );
         expect(existsDuringTest, isNot(isNull));
@@ -136,7 +136,7 @@ void main() {
               return 'q';
             },
           ),
-          const Barrier('Application finished.'),
+          Barrier('Application finished.'),
         ],
         logging:
             false, // we ignore leading log lines to avoid making this test sensitive to e.g. the help message text
@@ -232,7 +232,7 @@ void main() {
               return 'q';
             },
           ),
-          const Barrier('Application finished.'),
+          Barrier('Application finished.'),
         ],
         logging:
             false, // we ignore leading log lines to avoid making this test sensitive to e.g. the help message text
@@ -391,7 +391,7 @@ void main() {
             return 'q';
           },
         ),
-        const Barrier('Application finished.'),
+        Barrier('Application finished.'),
       ],
     );
     expect(result.exitCode, 0);

packages/flutter_tools/test/integration.shard/transition_test_utils.dart

@@ -43,48 +43,56 @@ abstract class Transition {
   bool matches(String line);
 
   @protected
-  bool lineMatchesPattern(String line, Pattern pattern) {
-    if (pattern is String) {
-      return line == pattern;
+  bool lineMatchesPattern(String line, Pattern pattern, bool contains) {
+    if (pattern is RegExp) {
+      // Ideally this would also distinguish between "contains" and "equals"
+      // operation.
+      return line.contains(pattern);
     }
-    return line.contains(pattern);
+    return contains ? line.contains(pattern) : line == pattern;
   }
 
   @protected
-  String describe(Pattern pattern) {
-    if (pattern is String) {
-      return '"$pattern"';
-    }
+  String describe(Pattern pattern, bool contains) {
     if (pattern is RegExp) {
       return '/${pattern.pattern}/';
     }
-    return '$pattern';
+    return contains ? '"...$pattern..."' : '"$pattern"';
   }
 }
 
 class Barrier extends Transition {
-  const Barrier(this.pattern, {super.handler, super.logging});
+  Barrier(this.pattern, {super.handler, super.logging}) : contains = false;
+  Barrier.contains(this.pattern, {super.handler, super.logging}) : contains = true;
+
   final Pattern pattern;
+  final bool contains;
 
   @override
-  bool matches(String line) => lineMatchesPattern(line, pattern);
+  bool matches(String line) => lineMatchesPattern(line, pattern, contains);
 
   @override
-  String toString() => describe(pattern);
+  String toString() => describe(pattern, contains);
 }
 
 class Multiple extends Transition {
   Multiple(List<Pattern> patterns, {super.handler, super.logging})
     : _originalPatterns = patterns,
-      patterns = patterns.toList();
+      patterns = patterns.toList(),
+      contains = false;
+  Multiple.contains(List<Pattern> patterns, {super.handler, super.logging})
+    : _originalPatterns = patterns,
+      patterns = patterns.toList(),
+      contains = true;
 
   final List<Pattern> _originalPatterns;
   final List<Pattern> patterns;
+  final bool contains;
 
   @override
   bool matches(String line) {
     for (int index = 0; index < patterns.length; index += 1) {
-      if (lineMatchesPattern(line, patterns[index])) {
+      if (lineMatchesPattern(line, patterns[index], contains)) {
         patterns.removeAt(index);
         break;
       }
@@ -94,6 +102,7 @@ class Multiple extends Transition {
 
   @override
   String toString() {
+    String describe(Pattern pattern) => super.describe(pattern, contains);
     if (patterns.isEmpty) {
       return '${_originalPatterns.map(describe).join(', ')} (all matched)';
     }