add test for draw endpoint

tests/test_it_draw.py

@@ -0,0 +1,25 @@
+from fastapi.testclient import TestClient
+from hayhooks.server import app
+from tests.test_it_deploy import deploy_pipeline
+from pathlib import Path
+
+client = TestClient(app)
+
+
+def test_draw_pipeline():
+    pipeline_file = Path(__file__).parent / "test_files" / "working_pipelines/test_pipeline_01.yml"
+    pipeline_data = {"name": pipeline_file.stem, "source_code": pipeline_file.read_text()}
+
+    deploy_response = deploy_pipeline(pipeline_data)
+    assert deploy_response.status_code == 200
+
+    draw_response = client.get(f"/draw/{pipeline_data['name']}")
+    assert draw_response.status_code == 200
+
+    assert draw_response.headers["Content-Type"] == "image/png"
+    assert len(draw_response.content) > 0
+
+
+def test_draw_non_existent_pipeline():
+    draw_response = client.get("/draw/non_existent_pipeline")
+    assert draw_response.status_code == 404