Fix local test failures in flutter_tools (#42015)

* Minor clean-up in terminal.dart

* Don't wrap text in tests (otherwise we'll be sensitive to the terminal width).

packages/flutter_tools/lib/src/base/terminal.dart

@@ -9,15 +9,6 @@ import '../globals.dart';
 import 'context.dart';
 import 'io.dart' as io;
 import 'platform.dart';
-import 'utils.dart';
-
-final AnsiTerminal _kAnsiTerminal = AnsiTerminal();
-
-AnsiTerminal get terminal {
-  return (context == null || context.get<AnsiTerminal>() == null)
-      ? _kAnsiTerminal
-      : context.get<AnsiTerminal>();
-}
 
 enum TerminalColor {
   red,
@@ -29,11 +20,15 @@ enum TerminalColor {
   grey,
 }
 
-final OutputPreferences _kOutputPreferences = OutputPreferences();
+AnsiTerminal get terminal {
+  return context?.get<AnsiTerminal>() ?? _defaultAnsiTerminal;
+}
+final AnsiTerminal _defaultAnsiTerminal = AnsiTerminal();
 
-OutputPreferences get outputPreferences => (context == null || context.get<OutputPreferences>() == null)
-    ? _kOutputPreferences
-    : context.get<OutputPreferences>();
+OutputPreferences get outputPreferences {
+  return context?.get<OutputPreferences>() ?? _defaultOutputPreferences;
+}
+final OutputPreferences _defaultOutputPreferences = OutputPreferences();
 
 /// A class that contains the context settings for command text output to the
 /// console.
@@ -42,31 +37,32 @@ class OutputPreferences {
     bool wrapText,
     int wrapColumn,
     bool showColor,
-  }) : wrapText = wrapText ?? io.stdio?.hasTerminal ?? const io.Stdio().hasTerminal,
+  }) : wrapText = wrapText ?? io.stdio.hasTerminal,
        _overrideWrapColumn = wrapColumn,
        showColor = showColor ?? platform.stdoutSupportsAnsi ?? false;
 
+  /// A version of this class for use in tests.
+  OutputPreferences.test() : wrapText = false, _overrideWrapColumn = null, showColor = false;
+
   /// If [wrapText] is true, then any text sent to the context's [Logger]
   /// instance (e.g. from the [printError] or [printStatus] functions) will be
   /// wrapped (newlines added between words) to be no longer than the
   /// [wrapColumn] specifies. Defaults to true if there is a terminal. To
   /// determine if there's a terminal, [OutputPreferences] asks the context's
-  /// stdio to see, and if that's not set, it tries creating a new [io.Stdio]
-  /// and asks it if there is a terminal.
+  /// stdio.
   final bool wrapText;
 
+  /// The terminal width used by the [wrapText] function if there is no terminal
+  /// attached to [io.Stdio], --wrap is on, and --wrap-columns was not specified.
+  static const int kDefaultTerminalColumns = 100;
+
   /// The column at which output sent to the context's [Logger] instance
   /// (e.g. from the [printError] or [printStatus] functions) will be wrapped.
   /// Ignored if [wrapText] is false. Defaults to the width of the output
   /// terminal, or to [kDefaultTerminalColumns] if not writing to a terminal.
-  /// To find out if we're writing to a terminal, it tries the context's stdio,
-  /// and if that's not set, it tries creating a new [io.Stdio] and asks it, if
-  /// that doesn't have an idea of the terminal width, then we just use a
-  /// default of 100. It will be ignored if [wrapText] is false.
   final int _overrideWrapColumn;
   int get wrapColumn {
-    return  _overrideWrapColumn ?? io.stdio?.terminalColumns
-      ?? const io.Stdio().terminalColumns ?? kDefaultTerminalColumns;
+    return _overrideWrapColumn ?? io.stdio.terminalColumns ?? kDefaultTerminalColumns;
   }
 
   /// Whether or not to output ANSI color codes when writing to the output

packages/flutter_tools/lib/src/base/utils.dart

@@ -307,9 +307,6 @@ class Poller {
 Future<List<T>> waitGroup<T>(Iterable<Future<T>> futures) {
   return Future.wait<T>(futures.where((Future<T> future) => future != null));
 }
-/// The terminal width used by the [wrapText] function if there is no terminal
-/// attached to [io.Stdio], --wrap is on, and --wrap-columns was not specified.
-const int kDefaultTerminalColumns = 100;
 
 /// Smallest column that will be used for text wrapping. If the requested column
 /// width is smaller than this, then this is what will be used.

packages/flutter_tools/test/src/context.dart

@@ -82,7 +82,7 @@ void testUsingContext(
             when(mock.getAttachedDevices()).thenAnswer((Invocation _) async => <IOSSimulator>[]);
             return mock;
           },
-          OutputPreferences: () => OutputPreferences(showColor: false),
+          OutputPreferences: () => OutputPreferences.test(),
           Logger: () => BufferLogger(),
           OperatingSystemUtils: () => FakeOperatingSystemUtils(),
           SimControl: () => MockSimControl(),

packages/flutter_tools/test/src/testbed.dart

@@ -33,7 +33,7 @@ final Map<Type, Generator> _testbedDefaults = <Type, Generator>{
   FileSystem: () => MemoryFileSystem(style: platform.isWindows ? FileSystemStyle.windows : FileSystemStyle.posix),
   Logger: () => BufferLogger(), // Allows reading logs and prevents stdout.
   OperatingSystemUtils: () => FakeOperatingSystemUtils(),
-  OutputPreferences: () => OutputPreferences(showColor: false), // configures BufferLogger to avoid color codes.
+  OutputPreferences: () => OutputPreferences.test(), // configures BufferLogger to avoid color codes.
   Usage: () => NoOpUsage(), // prevent addition of analytics from burdening test mocks
   FlutterVersion: () => FakeFlutterVersion(), // prevent requirement to mock git for test runner.
   Signals: () => FakeSignals(),  // prevent registering actual signal handlers.