fix(node): fetch default branch from env

Fixes #1072

noxfile.py

@@ -37,6 +37,6 @@ def lint(session):
 
 @nox.session(python=['3.6', '3.8'])
 def test(session):
-    session.install('pytest', 'pytest-cov', 'requests_mock', 'watchdog')
+    session.install('pytest', 'pytest-cov', 'watchdog')
     session.run('pip', 'install', '-e', '.')
     session.run('pytest', '--cov-report', 'term-missing', '--cov', 'autosynth', 'synthtool', 'tests', *session.posargs)

synthtool/gcp/common.py

@@ -370,7 +370,6 @@ def _load_repo_metadata(metadata_file: str = "./.repo-metadata.json") -> Dict:
 
 
 def _get_default_branch_name(repository_name: str) -> str:
-    github_req = requests.get(f"https://api.github.com/repos/{repository_name}")
-    github_req.raise_for_status()
-
-    return github_req.json()["default_branch"]
+    # This default should be switched to "main" once we've migrated
+    # the majority of our repositories:
+    return os.getenv("DEFAULT_BRANCH", "master")

tests/test_common.py

@@ -16,10 +16,9 @@
 from pathlib import Path
 from pytest import raises
 import os
-import requests_mock
 import synthtool as s
 from . import util
-
+from unittest import mock
 
 MOCK = Path(__file__).parent / "generationmock"
 template_dir = Path(__file__).parent.parent / "synthtool/gcp/templates"
@@ -43,10 +42,7 @@ def test_handles_empty_string():
 
 
 def test_get_default_branch():
-    with requests_mock.Mocker() as m:
-        m.get(
-            "https://api.github.com/repos/repo_name", text='{"default_branch": "main"}',
-        )
+    with mock.patch.dict(os.environ, {"DEFAULT_BRANCH": "main"}):
         assert _get_default_branch_name("repo_name") == "main"