Turn on the "isEmpty" and "isNotEmpty" lints and fix violations.

Change-Id: Ia6d957ebcc2b19f8043fa58f0c6e2202b2c1104f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/160982
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Karl Klose <karlklose@google.com>

pkg/test_runner/analysis_options.yaml

@@ -8,8 +8,6 @@ linter:
 #    - non_constant_identifier_names
 #    - only_throw_errors
 #    - prefer_interpolation_to_compose_strings
-#    - prefer_is_empty
-#    - prefer_is_not_empty
 #    - prefer_single_quotes
     - avoid_bool_literals_in_conditional_expressions
     - avoid_empty_else
@@ -60,6 +58,8 @@ linter:
     - prefer_final_fields
     - prefer_generic_function_type_aliases
     - prefer_initializing_formals
+    - prefer_is_empty
+    - prefer_is_not_empty
     - prefer_null_aware_operators
     - prefer_typing_uninitialized_variables
     - recursive_getters

pkg/test_runner/lib/src/android.dart

@@ -382,7 +382,7 @@ class AdbDevicePool {
   static Future<AdbDevicePool> create() async {
     var names = await AdbHelper.listDevices();
     var devices = names.map((id) => AdbDevice(id)).toList();
-    if (devices.length == 0) {
+    if (devices.isEmpty) {
       throw Exception('No android devices found. '
           'Please make sure "adb devices" shows your device!');
     }

pkg/test_runner/lib/src/browser.dart

@@ -54,7 +54,7 @@ String pathToJSIdentifier(String path) {
 
 /// Escape [name] to make it into a valid identifier.
 String _toJSIdentifier(String name) {
-  if (name.length == 0) return r'$';
+  if (name.isEmpty) return r'$';
 
   // Escape any invalid characters
   StringBuffer buffer;

pkg/test_runner/lib/src/browser_controller.dart

@@ -1105,7 +1105,7 @@ class BrowserTestRunner {
   }
 
   void printDoubleReportingTests() {
-    if (doubleReportingOutputs.length == 0) return;
+    if (doubleReportingOutputs.isEmpty) return;
     // TODO(ricow): die on double reporting.
     // Currently we just report this here, we could have a callback to the
     // encapsulating environment.

pkg/test_runner/lib/src/options.dart

@@ -504,7 +504,7 @@ compiler.''',
 
         case _OptionValueType.string:
           // Validate against the allowed values.
-          if (!option.values.isEmpty) {
+          if (option.values.isNotEmpty) {
             validate(String value) {
               if (!option.values.contains(value)) {
                 _fail('Unknown value "$value" for option "$command".');

pkg/test_runner/lib/src/path.dart

@@ -200,7 +200,7 @@ class Path {
     var isAbs = isAbsolute;
     var segs = segments();
     String drive;
-    if (isAbs && !segs.isEmpty && segs[0].length == 2 && segs[0][1] == ':') {
+    if (isAbs && segs.isNotEmpty && segs[0].length == 2 && segs[0][1] == ':') {
       drive = segs[0];
       segs.removeRange(0, 1);
     }

pkg/test_runner/lib/src/process_queue.dart

@@ -405,7 +405,7 @@ class CommandQueue {
   void _tryRunNextCommand() {
     _checkDone();
 
-    if (_numProcesses < _maxProcesses && !_runQueue.isEmpty) {
+    if (_numProcesses < _maxProcesses && _runQueue.isNotEmpty) {
       var command = _runQueue.removeFirst();
       var isBrowserCommand = command is BrowserTestCommand;
 

pkg/test_runner/lib/src/reset_safari.dart

@@ -143,7 +143,7 @@ Future<Null> killSafari({Uri bundle}) async {
   if (result.exitCode == 0) {
     var stdout = result.stdout as String;
     var pids =
-        stdout.split("\n").where((String line) => !line.isEmpty).toList();
+        stdout.split("\n").where((String line) => line.isNotEmpty).toList();
     var timer = Timer(const Duration(seconds: 10), () {
       print("Kill -9 Safari $pids");
       kill(pids, force: true);

pkg/test_runner/lib/src/test_case.dart

@@ -113,7 +113,7 @@ class TestCase {
   }
 
   CommandOutput get lastCommandOutput {
-    if (commandOutputs.length == 0) {
+    if (commandOutputs.isEmpty) {
       throw Exception("CommandOutputs is empty, maybe no command was run? ("
           "displayName: '$displayName', "
           "configurationString: '$configurationString')");
@@ -122,7 +122,7 @@ class TestCase {
   }
 
   Command get lastCommandExecuted {
-    if (commandOutputs.length == 0) {
+    if (commandOutputs.isEmpty) {
       throw Exception("CommandOutputs is empty, maybe no command was run? ("
           "displayName: '$displayName', "
           "configurationString: '$configurationString')");

pkg/test_runner/lib/src/test_configurations.dart

@@ -254,7 +254,7 @@ Future testConfigurations(List<TestConfiguration> configurations) async {
   }
 
   // Start all the HTTP servers required before starting the process queue.
-  if (!serverFutures.isEmpty) {
+  if (serverFutures.isNotEmpty) {
     await Future.wait(serverFutures);
   }
 

pkg/test_runner/lib/src/test_suite.dart

@@ -595,14 +595,14 @@ class StandardTestSuite extends TestSuite {
     var commonArguments = _commonArgumentsFromFile(testFile);
 
     var vmOptionsList = getVmOptions(testFile);
-    assert(!vmOptionsList.isEmpty);
+    assert(vmOptionsList.isNotEmpty);
 
     for (var vmOptionsVariant = 0;
         vmOptionsVariant < vmOptionsList.length;
         vmOptionsVariant++) {
       var vmOptions = vmOptionsList[vmOptionsVariant];
       var allVmOptions = vmOptions;
-      if (!extraVmOptions.isEmpty) {
+      if (extraVmOptions.isNotEmpty) {
         allVmOptions = vmOptions.toList()..addAll(extraVmOptions);
       }
 
@@ -623,7 +623,7 @@ class StandardTestSuite extends TestSuite {
     var commonArguments = _commonArgumentsFromFile(testFile);
 
     var vmOptionsList = getVmOptions(testFile);
-    assert(!vmOptionsList.isEmpty);
+    assert(vmOptionsList.isNotEmpty);
 
     var emitDdsTest = false;
     for (var i = 0; i < 2; ++i) {
@@ -632,7 +632,7 @@ class StandardTestSuite extends TestSuite {
           vmOptionsVariant++) {
         var vmOptions = vmOptionsList[vmOptionsVariant];
         var allVmOptions = vmOptions;
-        if (!extraVmOptions.isEmpty) {
+        if (extraVmOptions.isNotEmpty) {
           allVmOptions = vmOptions.toList()..addAll(extraVmOptions);
         }
         if (emitDdsTest) {

pkg/test_runner/lib/src/testing_servers.dart

@@ -241,7 +241,7 @@ class TestingServers {
   Uri _getFileUriFromRequestUri(Uri request) {
     // Go to the top of the file to see an explanation of the URL path scheme.
     var pathSegments = request.normalizePath().pathSegments;
-    if (pathSegments.length == 0) return null;
+    if (pathSegments.isEmpty) return null;
     var packagesIndex = pathSegments.indexOf('packages');
     if (packagesIndex != -1) {
       var packageUri = Uri(

pkg/test_runner/lib/src/vendored_pkg/args/src/parser.dart

@@ -50,7 +50,7 @@ class Parser {
     });
 
     // Parse the args.
-    while (args.length > 0) {
+    while (args.isNotEmpty) {
       if (current == '--') {
         // Reached the argument terminator, so stop here.
         args.removeAt(0);
@@ -98,7 +98,7 @@ class Parser {
   /// that there is a valid value there.
   void readNextArgAsValue(Option option) {
     // Take the option argument from the next command line arg.
-    validate(args.length > 0, 'Missing argument for "${option.name}".');
+    validate(args.isNotEmpty, 'Missing argument for "${option.name}".');
 
     // Make sure it isn't an option itself.
     validate(!_ABBR_OPT.hasMatch(current) && !_LONG_OPT.hasMatch(current),

pkg/test_runner/lib/src/vendored_pkg/args/src/usage.dart

@@ -144,11 +144,11 @@ class Usage {
     var lines = text.split('\n');
 
     // Strip leading and trailing empty lines.
-    while (lines.length > 0 && lines[0].trim() == '') {
+    while (lines.isNotEmpty && lines[0].trim() == '') {
       lines.removeRange(0, 1);
     }
 
-    while (lines.length > 0 && lines[lines.length - 1].trim() == '') {
+    while (lines.isNotEmpty && lines[lines.length - 1].trim() == '') {
       lines.removeLast();
     }