[ dart:io ] Added override for exit(...) in IOOverrides

This will allow for `package:test` to handle test cases which call
`exit(...)` without the test suite being aborted due to the VM shutting
down.

See dart-lang/test#2248

Change-Id: I09e78460d2b87ba7ea755d7538a1446ecb566d0b
CoreLibraryReviewExempt: Only adds override behavior, does not change API surface.
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/377380
Commit-Queue: Ben Konyi <[email protected]>
Reviewed-by: Brian Quinlan <[email protected]>

Author: bkonyi

CHANGELOG.md

@@ -26,6 +26,7 @@
 
 - **Breaking Change** [#56468][]: Marked `IOOverrides` as an `abstract base`
   class.
+- Added ability to override behavior of `exit(...)` to `IOOverrides`.
 
 [#56468]: https://github.com/dart-lang/sdk/issues/56468
 

sdk/lib/io/overrides.dart

@@ -108,6 +108,9 @@ abstract base class IOOverrides {
     Stdin Function()? stdin,
     Stdout Function()? stdout,
     Stdout Function()? stderr,
+
+    // Process exit
+    @Since("3.10") Never Function(int)? exit,
   }) {
     // Avoid building chains of override scopes. Just copy outer scope's
     // functions and `_previous`.
@@ -156,6 +159,9 @@ abstract base class IOOverrides {
       stdin ?? currentScope?._stdin,
       stdout ?? currentScope?._stdout,
       stderr ?? currentScope?._stderr,
+
+      // Process exit
+      exit ?? currentScope?._exit,
     );
     return dart_async.runZoned<R>(
       body,
@@ -292,7 +298,7 @@ abstract base class IOOverrides {
 
   /// Asynchronously returns a [Socket] connected to the given host and port.
   ///
-  /// When this override is installed, this functions overrides the behavior of
+  /// When this override is installed, this function overrides the behavior of
   /// `Socket.connect(...)`.
   Future<Socket> socketConnect(
     host,
@@ -313,7 +319,7 @@ abstract base class IOOverrides {
   /// Asynchronously returns a [ConnectionTask] that connects to the given host
   /// and port when successful.
   ///
-  /// When this override is installed, this functions overrides the behavior of
+  /// When this override is installed, this function overrides the behavior of
   /// `Socket.startConnect(...)`.
   Future<ConnectionTask<Socket>> socketStartConnect(
     host,
@@ -334,7 +340,7 @@ abstract base class IOOverrides {
   /// Asynchronously returns a [ServerSocket] that connects to the given address
   /// and port when successful.
   ///
-  /// When this override is installed, this functions overrides the behavior of
+  /// When this override is installed, this function overrides the behavior of
   /// `ServerSocket.bind(...)`.
   Future<ServerSocket> serverSocketBind(
     address,
@@ -352,6 +358,22 @@ abstract base class IOOverrides {
     );
   }
 
+  // Process exit
+
+  /// Exit the Dart VM process immediately with the given exit code.
+  ///
+  /// When this override is installed, this function overrides the behavior of
+  /// `exit(...)`.
+  @Since("3.10")
+  Never exit(int code) {
+    if (!_EmbedderConfig._mayExit) {
+      throw new UnsupportedError(
+        "This embedder disallows calling dart:io's exit()",
+      );
+    }
+    _ProcessUtils._exit(code);
+  }
+
   // Standard streams
 
   /// The standard input stream of data read by this program.
@@ -440,6 +462,9 @@ final class _IOOverridesScope extends IOOverrides {
   final Stdout Function()? _stdout;
   final Stdout Function()? _stderr;
 
+  // Process exit
+  final Never Function(int)? _exit;
+
   _IOOverridesScope(
     this._previous,
 
@@ -480,6 +505,9 @@ final class _IOOverridesScope extends IOOverrides {
     this._stdin,
     this._stdout,
     this._stderr,
+
+    // Process exit
+    this._exit,
   );
 
   // Directory
@@ -662,6 +690,11 @@ final class _IOOverridesScope extends IOOverrides {
         shared: shared,
       );
 
+  // Process exit
+  @override
+  Never exit(int code) =>
+      _exit?.call(code) ?? _previous?.exit.call(code) ?? super.exit(code);
+
   // Standard streams
   @override
   Stdin get stdin => _stdin?.call() ?? _previous?.stdin ?? super.stdin;

sdk/lib/io/process.dart

@@ -51,13 +51,16 @@ class _ProcessUtils {
 /// program to the surrounding environment. This will avoid any
 /// cross-platform issues.
 Never exit(int code) {
-  ArgumentError.checkNotNull(code, "code");
-  if (!_EmbedderConfig._mayExit) {
-    throw new UnsupportedError(
-      "This embedder disallows calling dart:io's exit()",
-    );
+  IOOverrides? overrides = IOOverrides.current;
+  if (overrides == null) {
+    if (!_EmbedderConfig._mayExit) {
+      throw new UnsupportedError(
+        "This embedder disallows calling dart:io's exit()",
+      );
+    }
+    _ProcessUtils._exit(code);
   }
-  _ProcessUtils._exit(code);
+  overrides.exit(code);
 }
 
 /// Set the global exit code for the Dart VM.
@@ -71,7 +74,6 @@ Never exit(int code) {
 /// See [exit] for more information on how to chose a value for the
 /// exit code.
 void set exitCode(int code) {
-  ArgumentError.checkNotNull(code, "code");
   _ProcessUtils._setExitCode(code);
 }
 

tests/standalone/io/io_override_test.dart

@@ -208,6 +208,10 @@ Future<ServerSocket> serverSocketBind(
   throw "";
 }
 
+Never exitOverride(int code) {
+  throw code;
+}
+
 class StdinMock extends Stream<List<int>> implements Stdin {
   bool echoMode = false;
   bool echoNewlineMode = false;
@@ -278,6 +282,7 @@ Future<Null> ioOverridesRunTest() async {
       Expect.isTrue(stdin is StdinMock);
       Expect.identical(stdout, stdoutMock);
       Expect.identical(stderr, stderrMock);
+      Expect.throws<int>(() => exit(42), (int code) => code == 42);
     },
     createDirectory: DirectoryMock.createDirectory,
     getCurrentDirectory: DirectoryMock.getCurrent,
@@ -299,6 +304,7 @@ Future<Null> ioOverridesRunTest() async {
     stdin: () => StdinMock(),
     stdout: () => stdoutMock,
     stderr: () => stderrMock,
+    exit: exitOverride,
   );
   Expect.isFalse(new Directory("directory") is DirectoryMock);
   Expect.isTrue(new Directory("directory") is Directory);