Add BlazeWorkspace.forBuild()

Change-Id: I2b896716c7dc7f53c400e6ea516ecf0439e347b3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/264723
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/workspace/blaze.dart

@@ -460,6 +460,25 @@ class BlazeWorkspace extends Workspace
     return null;
   }
 
+  /// Create the Blaze workspace with the given [root].
+  ///
+  /// This method should be used during build in google3, when we know for
+  /// sure the workspace root, but [file_paths.blazeWorkspaceMarker] is not
+  /// available.
+  static BlazeWorkspace forBuild({
+    required Folder root,
+  }) {
+    var provider = root.provider;
+    var blazeBin = root.getChildAssumingFolder('blaze-bin');
+    var blazeGenfiles = root.getChildAssumingFolder('blaze-genfiles');
+
+    var binPaths = _findBinFolderPaths(root);
+    binPaths.add(blazeBin.path);
+
+    return BlazeWorkspace._(provider, root.path, binPaths, blazeGenfiles.path,
+        lookForBuildFileSubstitutes: true);
+  }
+
   /// Find the "bin" folder path, by searching for it.
   ///
   /// Depending on the environment we're working in (source code tree, build

pkg/analyzer/test/src/workspace/blaze_test.dart

@@ -980,6 +980,16 @@ class BlazeWorkspaceTest with ResourceProviderMixin {
         equals: '/workspace/blaze-genfiles/my/module/test3.dart');
   }
 
+  void test_forBuild() {
+    // We don't have to create any resources, `forBuild()` does not check.
+    var workspace = BlazeWorkspace.forBuild(
+      root: getFolder('/workspace'),
+    );
+    expect(workspace.root, convertPath('/workspace'));
+    expect(workspace.binPaths.single, convertPath('/workspace/blaze-bin'));
+    expect(workspace.genfiles, convertPath('/workspace/blaze-genfiles'));
+  }
+
   /// Create new files and directories from [paths].
   void _addResources(List<String> paths) {
     for (String path in paths) {