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

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

Index: sdk/lib/_internal/pub/test/cache/repair/reinstalls_hosted_packages_test.dart
diff --git a/sdk/lib/_internal/pub/test/cache/repair/reinstalls_hosted_packages_test.dart b/sdk/lib/_internal/pub/test/cache/repair/reinstalls_hosted_packages_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5df38af17d0ad6ea5f46851f600018a6d3bfc9dc
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/cache/repair/reinstalls_hosted_packages_test.dart
@@ -0,0 +1,56 @@
+// 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 '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration('reinstalls previously cached hosted packages', () {
+    servePackages([
+      packageMap("foo", "1.2.3"),
+      packageMap("foo", "1.2.4"),
+      packageMap("foo", "1.2.5"),
+      packageMap("bar", "1.2.3"),
+      packageMap("bar", "1.2.4")
+    ]);
+
+    // Set up a cache with some broken 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-1.2.5", [
+            d.libPubspec("foo", "1.2.5"),
+            d.file("broken.txt")
+          ]),
+          d.dir("bar-1.2.4", [
+            d.libPubspec("bar", "1.2.4"),
+            d.file("broken.txt")
+          ])
+        ])))
+      ])
+    ]).create();
+
+    // Repair them.
+    schedulePub(args: ["cache", "repair"],
+        output: '''
+          Downloading bar 1.2.4...
+          Downloading foo 1.2.3...
+          Downloading foo 1.2.5...
+          Reinstalled 3 packages.''');
+
+    // The broken versions should have been replaced.
+    d.hostedCache([
+      d.dir("bar-1.2.4", [d.nothing("broken.txt")]),
+      d.dir("foo-1.2.3", [d.nothing("broken.txt")]),
+      d.dir("foo-1.2.5", [d.nothing("broken.txt")])
+    ]).validate();
+  });
+}