fix: don't write a .gitignore unless the directory is empty

3 files changed, 17 insertions, 3 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 8ac4997b..670f3363 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -24,6 +24,10 @@ Unreleased
 
 - Dropped support for Python 3.6, which ended support on 2021-12-23.
 
+- Fix: a .gitignore file will only be written into the HTML report output
+  directory if the directory is empty.  This should prevent certain unfortunate
+  accidents of writing the file where it is not wanted.
+
 - Releases now have MacOS arm64 wheels for Apple Silicon (fixes `issue 1288`_).
 
 .. _issue 1288: https://github.com/nedbat/coveragepy/issues/1288
diff --git a/coverage/html.py b/coverage/html.py
index ae1d041f..342d2ad1 100644
--- a/coverage/html.py
+++ b/coverage/html.py
@@ -164,6 +164,7 @@ class HtmlReporter:
         self.incr = IncrementalChecker(self.directory)
         self.datagen = HtmlDataGeneration(self.coverage)
         self.totals = Numbers(precision=self.config.precision)
+        self.directory_was_empty = False
 
         self.template_globals = {
             # Functions available in the templates.
@@ -224,11 +225,11 @@ class HtmlReporter:
         for static in self.STATIC_FILES:
             shutil.copyfile(data_filename(static), os.path.join(self.directory, static))
 
+        # Only write the .gitignore file if the directory was originally empty.
         # .gitignore can't be copied from the source tree because it would
         # prevent the static files from being checked in.
-        gitigore_path = os.path.join(self.directory, ".gitignore")
-        if not os.path.exists(gitigore_path):
-            with open(gitigore_path, "w") as fgi:
+        if self.directory_was_empty:
+            with open(os.path.join(self.directory, ".gitignore"), "w") as fgi:
                 fgi.write("# Created by coverage.py\n*\n")
 
         # The user may have extra CSS they want copied.
@@ -240,6 +241,8 @@ class HtmlReporter:
         rootname = flat_rootname(fr.relative_filename())
         html_filename = rootname + ".html"
         ensure_dir(self.directory)
+        if not os.listdir(self.directory):
+            self.directory_was_empty = True
         html_path = os.path.join(self.directory, html_filename)
 
         # Get the numbers for this file.
diff --git a/tests/test_html.py b/tests/test_html.py
index cb222270..797fee1d 100644
--- a/tests/test_html.py
+++ b/tests/test_html.py
@@ -291,6 +291,13 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         with open("htmlcov/.gitignore") as fgi:
             assert fgi.read() == "# ignore nothing"
 
+    def test_dont_write_gitignore_into_existing_directory(self):
+        self.create_initial_files()
+        self.make_file("htmlcov/README", "My files: don't touch!")
+        self.run_coverage()
+        self.assert_doesnt_exist("htmlcov/.gitignore")
+        self.assert_exists("htmlcov/index.html")
+
 
 class HtmlTitleTest(HtmlTestHelpers, CoverageTest):
     """Tests of the HTML title support."""