test: cover empty company fallback

Add a markdown test that expects "-" when company is empty.

Signed-off-by: Venu Vardhan Reddy Tekula <venuvrtekula@gmail.com>

Author: vchrombie

test_markdown.py

@@ -148,6 +148,60 @@ def test_write_to_markdown_with_sponsors(
         )
         mock_file().write.assert_called_once_with(expected_content)
 
+    @patch(
+        "markdown.os.environ.get", return_value=None
+    )  # Mock GITHUB_STEP_SUMMARY to None
+    @patch("builtins.open", new_callable=mock_open)
+    def test_write_to_markdown_empty_company_falls_back(
+        self, mock_file, mock_env_get
+    ):  # pylint: disable=unused-argument
+        """
+        Test the write_to_markdown function with an empty company value.
+        """
+        person1 = contributor_stats.ContributorStats(
+            "user1",
+            "",
+            False,
+            "url",
+            100,
+            "commit url",
+            "sponsor_url_1",
+        )
+        collaborators = [
+            person1,
+        ]
+        ghe = ""
+
+        write_to_markdown(
+            collaborators,
+            "filename",
+            "2023-01-01",
+            "2023-01-02",
+            None,
+            "org/repo",
+            "false",
+            True,
+            ghe,
+        )
+
+        mock_file.assert_called_once_with("filename", "w", encoding="utf-8")
+        expected_content = (
+            "# Contributors\n\n"
+            "- Date range for contributor list:  2023-01-01 to 2023-01-02\n"
+            "- Repository: org/repo\n\n"
+            "| Total Contributors | Total Contributions | % New Contributors |\n"
+            "| --- | --- | --- |\n"
+            "| 1 | 100 | 0.0% |\n\n"
+            "| Username | Company | All Time Contribution Count | New Contributor | "
+            "Commits between 2023-01-01 and 2023-01-02 |\n"
+            "| --- | --- | --- | --- | --- |\n"
+            "| @user1 | - | 100 | False | commit url |\n"
+            "\n _this file was generated by the "
+            "[Contributors GitHub Action]"
+            "(https://github.com/github/contributors)_\n"
+        )
+        mock_file().write.assert_called_once_with(expected_content)
+
     @patch(
         "markdown.os.environ.get", return_value=None
     )  # Mock GITHUB_STEP_SUMMARY to None