1 files changed, 53 insertions, 0 deletions
diff --git a/testing/tools/pdfium_root.py b/testing/tools/pdfium_root.py
new file mode 100644
index 000000000..7c4c86130
--- /dev/null
+++ b/testing/tools/pdfium_root.py
@@ -0,0 +1,53 @@
+# Copyright 2022 The PDFium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Utilities for working with the PDFium tree's root directory."""
+
+import os
+import sys
+
+
+class RootDirectoryFinder:
+  """Finds the PDFium tree's root directories.
+
+  The implementation expects that either:
+  1. PDFium is a standalone checkout.
+  2. PDFium is part of another tree within a "third_party/pdfium" directory.
+
+  Attributes:
+      pdfium_root: The path to the root of the PDFium tree.
+      source_root: The path to the root of the source tree. May differ from
+        `pdfium_root` if PDFium is a third-party dependency in another tree.
+  """
+
+  def __init__(self):
+    # Expect `self_dir` to be ".../testing/tools".
+    self_dir = os.path.dirname(os.path.realpath(__file__))
+
+    self.pdfium_root = _remove_path_suffix(self_dir, ('testing', 'tools'))
+    if not self.pdfium_root:
+      raise Exception('Cannot find testing/tools within PDFium root directory')
+
+    # In a Chromium checkout, expect `self.pdfium_root` to be
+    # ".../third_party/pdfium".
+    self.source_root = _remove_path_suffix(self.pdfium_root,
+                                           ('third_party', 'pdfium'))
+    if not self.source_root:
+      self.source_root = self.pdfium_root
+
+
+def _remove_path_suffix(path, expected_suffix):
+  for expected_part in reversed(expected_suffix):
+    if os.path.basename(path) != expected_part:
+      return None
+    path = os.path.dirname(path)
+  return path
+
+
+def add_source_directory_to_import_path(source_directory_path):
+  """Adds a source root-relative directory to end of the import path."""
+  root_finder = RootDirectoryFinder()
+  path = os.path.realpath(
+      os.path.join(root_finder.source_root, source_directory_path))
+  if path not in sys.path:
+    sys.path.append(path)