bf: do not clobber existing .gitignore (#3105)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Vinicius D. Cerutti <[email protected]>

Author: 3 people

src/_nebari/stages/bootstrap/__init__.py

@@ -13,9 +13,14 @@
 
 def gen_gitignore():
     """
-    Generate `.gitignore` file.
-    Add files as needed.
+    Generate `.gitignore` file if not present.
     """
+    gitignore_path = pathlib.Path(".gitignore")
+
+    # If .gitignore already exists, don't overwrite it
+    if gitignore_path.exists():
+        return {}
+
     filestoignore = """
         # ignore terraform state
         .terraform
@@ -26,7 +31,7 @@ def gen_gitignore():
         # python
         __pycache__
     """
-    return {pathlib.Path(".gitignore"): cleandoc(filestoignore)}
+    return {gitignore_path: cleandoc(filestoignore)}
 
 
 def gen_cicd(config: schema.Main):

tests/tests_unit/conftest.py

@@ -1,3 +1,4 @@
+import os
 from pathlib import Path
 from unittest.mock import Mock
 
@@ -182,10 +183,19 @@ def nebari_stages():
 def nebari_render(nebari_config, nebari_stages, tmp_path):
     NEBARI_CONFIG_FN = "nebari-config.yaml"
 
-    config_filename = tmp_path / NEBARI_CONFIG_FN
-    write_configuration(config_filename, nebari_config)
-    render_template(tmp_path, nebari_config, nebari_stages)
-    return tmp_path, config_filename
+    # Save original cwd and change to tmp_path so files that should be generated
+    # in the repo root are put in the right place
+    original_cwd = Path.cwd()
+    os.chdir(tmp_path)
+
+    try:
+        config_filename = tmp_path / NEBARI_CONFIG_FN
+        write_configuration(config_filename, nebari_config)
+        render_template(tmp_path, nebari_config, nebari_stages)
+        return tmp_path, config_filename
+    finally:
+        # Always restore original cwd
+        os.chdir(original_cwd)
 
 
 @pytest.fixture

tests/tests_unit/test_bootstrap.py

@@ -0,0 +1,67 @@
+import os
+import pathlib
+from unittest.mock import patch
+
+from _nebari.stages.bootstrap import gen_gitignore
+
+
+class TestGenGitignore:
+    """Test the gen_gitignore function."""
+
+    def test_gen_gitignore_creates_file_when_not_exists(self, tmp_path):
+        """Test that gen_gitignore returns gitignore content when file doesn't exist."""
+        with patch("pathlib.Path.exists", return_value=False):
+            result = gen_gitignore()
+
+        assert pathlib.Path(".gitignore") in result
+        assert "terraform.tfstate" in result[pathlib.Path(".gitignore")]
+        assert "__pycache__" in result[pathlib.Path(".gitignore")]
+
+    def test_gen_gitignore_skips_when_exists(self, tmp_path):
+        """Test that gen_gitignore returns empty dict when .gitignore already exists."""
+        with patch("pathlib.Path.exists", return_value=True):
+            result = gen_gitignore()
+
+        assert result == {}
+
+    def test_gen_gitignore_content_format(self, tmp_path):
+        """Test that gen_gitignore returns properly formatted content."""
+        with patch("pathlib.Path.exists", return_value=False):
+            result = gen_gitignore()
+
+        content = result[pathlib.Path(".gitignore")]
+        expected_patterns = [
+            "# ignore terraform state",
+            ".terraform",
+            "terraform.tfstate",
+            "terraform.tfstate.backup",
+            ".terraform.tfstate.lock.info",
+            "# python",
+            "__pycache__",
+        ]
+
+        for pattern in expected_patterns:
+            assert pattern in content
+
+    def test_gen_gitignore_file_system_integration(self, tmp_path):
+        """Test gen_gitignore behavior with actual file system."""
+        # Change to tmp directory
+        original_cwd = pathlib.Path.cwd()
+        os.chdir(tmp_path)
+
+        try:
+            # Test when .gitignore doesn't exist
+            result = gen_gitignore()
+            assert pathlib.Path(".gitignore") in result
+
+            # Create .gitignore file
+            gitignore_path = tmp_path / ".gitignore"
+            gitignore_path.write_text("existing content")
+
+            # Test when .gitignore exists
+            result = gen_gitignore()
+            assert result == {}
+
+        finally:
+            # Restore original working directory
+            os.chdir(original_cwd)