Add “pub cache repair” to forcibly re-install previously cached packages.

sdk/lib/_internal/pub/test/cache/repair/handles_failure_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub_tests;
+
+import 'package:scheduled_test/scheduled_test.dart';
+import 'package:scheduled_test/scheduled_stream.dart';
+
+import '../../../lib/src/exit_codes.dart' as exit_codes;
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration('handles failure to reinstall some packages', () {
+    // Only serve two packages so repairing will have a failure.
+    servePackages([
+      packageMap("foo", "1.2.3"),
+      packageMap("foo", "1.2.5")
+    ]);
+
+    // Set up a cache with some packages.
+    d.dir(cachePath, [
+      d.dir('hosted', [
+        d.async(port.then((p) => d.dir('127.0.0.1%58$p', [
+          d.dir("foo-1.2.3", [
+            d.libPubspec("foo", "1.2.3"),
+            d.file("broken.txt")
+          ]),
+          d.dir("foo-1.2.4", [
+            d.libPubspec("foo", "1.2.4"),
+            d.file("broken.txt")
+          ]),
+          d.dir("foo-1.2.5", [
+            d.libPubspec("foo", "1.2.5"),
+            d.file("broken.txt")
+          ])
+        ])))
+      ])
+    ]).create();
+
+    // Repair them.
+    var pub = startPub(args: ["cache", "repair"]);
+
+    pub.stdout.expect("Downloading foo 1.2.3...");
+    pub.stdout.expect("Downloading foo 1.2.4...");
+    pub.stdout.expect("Downloading foo 1.2.5...");
+
+    pub.stderr.expect(startsWith("Failed to repair foo 1.2.4 from"));
+    pub.stderr.expect("HTTP error 404: Not Found");
+
+    pub.stdout.expect("Reinstalled 2 packages.");
+    pub.stdout.expect("Failed to reinstall 1 package.");
+
+    pub.shouldExit(exit_codes.UNAVAILABLE);
+  });
+}