Fix path_to_urls test on Mac.

sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart

Index: sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart b/sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart
index ce6b6208dff4a1f1d656e01a068faada288f03de..5ab621385f8c3b2ceb40c6179f5233d298beda5c 100644
--- a/sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart
+++ b/sdk/lib/_internal/pub/test/serve/web_socket/path_to_urls_test.dart
@@ -7,6 +7,7 @@ library pub_tests;
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
+import '../../../lib/src/io.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../utils.dart';
@@ -130,10 +131,15 @@ main() {
       getServerUrl("randomdir", "packages/foo/foo.dart")
     ]});
 
+    // Note: Using canonicalize here because pub gets the path to the
+    // entrypoint package from the working directory, which has had symlinks
+    // resolve. On Mac, "/tmp" is actually a symlink to "/private/tmp", so we
+    // need to accomodate that.
+
     // An absolute path to another package's lib/ directory.
     expectWebSocketCall({
       "command": "pathToUrls",
-      "path": p.join(sandboxDir, "foo", "lib", "foo.dart")
+      "path": canonicalize(p.join(sandboxDir, "foo", "lib", "foo.dart"))
     }, replyEquals: {"urls": [
       getServerUrl("test", "packages/foo/foo.dart"),
       getServerUrl("web", "packages/foo/foo.dart"),
@@ -153,7 +159,7 @@ main() {
     // An absolute path to another package's asset/ directory.
     expectWebSocketCall({
       "command": "pathToUrls",
-      "path": p.join(sandboxDir, "foo", "asset", "foo.dart")
+      "path": canonicalize(p.join(sandboxDir, "foo", "asset", "foo.dart"))
     }, replyEquals: {"urls": [
       getServerUrl("test", "assets/foo/foo.dart"),
       getServerUrl("web", "assets/foo/foo.dart"),