Add Unit Tests (#132)

* Add tests and new github workflow

* Add new unit tests

* Add Github CI workflow

* Workflow fix

* Add pytest install to workflow file

* More CI / test updates

* More test cleanup

* Whitespace cleanup and link complexity override

* More whitespace cleanup

* Make lint less strict

* More lint tweaks

tests/test_preview_manager.py

@@ -0,0 +1,169 @@
+from unittest.mock import MagicMock, patch
+
+from src.api.preview_manager import PreviewManager
+
+
+def make_mock_job(job_id='test-job-1', input_path='/tmp/test.blend',
+                  file_list=None, **kwargs):
+    job = MagicMock()
+    job.id = job_id
+    job.input_path = input_path
+    job.file_list.return_value = file_list or []
+    for k, v in kwargs.items():
+        setattr(job, k, v)
+    return job
+
+
+class TestPreviewManagerDefaults:
+    """Default state."""
+
+    def test_storage_path_none_initially(self, preview_manager_instance):
+        assert preview_manager_instance.storage_path is not None
+
+    def test_running_jobs_empty_initially(self, preview_manager_instance):
+        assert preview_manager_instance._running_jobs == {}
+
+
+class TestGeneratePreviewWorker:
+    """Core preview generation logic."""
+
+    def test_skips_when_no_supported_files(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job(file_list=[str(tmp_path / 'output.txt')])
+
+        with patch.object(preview_manager_instance, '_generate_job_preview_worker') as mock_gen:
+            preview_manager_instance._update_previews_for_job(job)
+            mock_gen.assert_called_once_with(job, False)
+
+    def test_uses_input_path_when_no_file_list(self, preview_manager_instance, tmp_path):
+        """When file_list is empty, falls back to input_path."""
+        job = make_mock_job(input_path=str(tmp_path / 'output.mp4'))
+
+        with patch.object(preview_manager_instance, '_generate_job_preview_worker') as mock_gen:
+            preview_manager_instance._update_previews_for_job(job)
+            mock_gen.assert_called_once()
+
+    def test_generate_preview_checks_existing_files(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job(input_path=str(tmp_path / 'test.jpg'))
+
+        with patch('src.api.preview_manager.save_first_frame') as mock_save:
+            with patch('src.api.preview_manager.os.path.exists', return_value=False):
+                preview_manager_instance._generate_job_preview_worker(job)
+
+            # No file_list → falls back to input_path → label is "input"
+            expected_img = str(tmp_path / f'{job.id}-input-480.jpg')
+            mock_save.assert_called_once_with(
+                source_path=job.input_path,
+                dest_path=expected_img,
+                max_width=480,
+            )
+
+
+class TestUpdatePreviewsForJob:
+    """Dispatch of preview generation."""
+
+    def test_starts_new_thread(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job(file_list=[str(tmp_path / 'test.mp4')])
+
+        with patch('src.api.preview_manager.threading.Thread') as mock_thread:
+            thread_instance = MagicMock()
+            mock_thread.return_value = thread_instance
+
+            preview_manager_instance._update_previews_for_job(job)
+
+            mock_thread.assert_called_once()
+            thread_instance.start.assert_called_once()
+            assert preview_manager_instance._running_jobs[job.id] == thread_instance
+
+    def test_reuses_existing_thread(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job()
+
+        existing_thread = MagicMock()
+        existing_thread.is_alive.return_value = True
+        preview_manager_instance._running_jobs[job.id] = existing_thread
+
+        with patch('src.api.preview_manager.threading.Thread') as mock_thread:
+            preview_manager_instance._update_previews_for_job(job)
+            mock_thread.assert_not_called()
+
+    def test_join_when_wait_requested(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job()
+
+        with patch('src.api.preview_manager.threading.Thread') as mock_thread:
+            thread_instance = MagicMock()
+            mock_thread.return_value = thread_instance
+
+            preview_manager_instance._update_previews_for_job(
+                job, wait_until_completion=True, timeout=30,
+            )
+            thread_instance.join.assert_called_once_with(timeout=30)
+
+
+class TestGetPreviewsForJob:
+    """Reading preview files."""
+
+    def test_returns_empty_when_no_previews(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job()
+
+        result = preview_manager_instance._get_previews_for_job(job)
+        assert result == {}
+
+    def test_returns_preview_files(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job(job_id='abc')
+
+        # Create a fake preview file
+        (tmp_path / 'abc-output-480.jpg').write_text('preview')
+
+        result = preview_manager_instance._get_previews_for_job(job)
+        assert 'output' in result
+        assert len(result['output']) == 1
+        assert result['output'][0]['kind'] == 'image'
+
+
+class TestDeletePreviewsForJob:
+    """Cleaning up preview files."""
+
+    def test_deletes_existing_previews(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job(job_id='abc')
+
+        preview_file = tmp_path / 'abc-output-480.jpg'
+        preview_file.write_text('preview')
+
+        preview_manager_instance._delete_previews_for_job(job)
+        assert not preview_file.exists()
+
+    def test_no_error_when_no_previews(self, preview_manager_instance, tmp_path):
+        preview_manager_instance.storage_path = str(tmp_path)
+        job = make_mock_job()
+        preview_manager_instance._delete_previews_for_job(job)
+
+
+class TestForwarders:
+    """Classmethod forwarders delegate to instance."""
+
+    def test_update_previews_for_job_forwarder(self, preview_manager_instance):
+        job = make_mock_job()
+        with patch.object(preview_manager_instance, '_update_previews_for_job') as mock_method:
+            PreviewManager.update_previews_for_job(job)
+            mock_method.assert_called_once_with(job, False, False, None)
+
+    def test_get_previews_for_job_forwarder(self, preview_manager_instance):
+        job = make_mock_job()
+        with patch.object(preview_manager_instance, '_get_previews_for_job',
+                          return_value={'input': []}) as mock_method:
+            result = PreviewManager.get_previews_for_job(job)
+            assert result == {'input': []}
+            mock_method.assert_called_once_with(job)
+
+    def test_delete_previews_for_job_forwarder(self, preview_manager_instance):
+        job = make_mock_job()
+        with patch.object(preview_manager_instance, '_delete_previews_for_job') as mock_method:
+            PreviewManager.delete_previews_for_job(job)
+            mock_method.assert_called_once_with(job)