DEVX-163: fix: check stdout for HTTP 500 in _run_push (docker sends to stdout)

tests/unit/test_build_image.py

@@ -288,7 +288,7 @@ class TestPushImage:
         """HTTP 500 from registry race condition — retry succeeds."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
         results = [
-            MagicMock(returncode=1, stderr="received unexpected HTTP status: 500 Internal Server Error", stdout=""),
+            MagicMock(returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"),
             MagicMock(returncode=0, stderr="", stdout=""),
         ]
         with (
@@ -303,7 +303,7 @@ class TestPushImage:
         """HTTP 500 retries exhausted — push fails, no delete attempted."""
         spec = ImageSpec(name="ci-base", dockerfile="Dockerfile", tags=["latest"])
         mock_result = MagicMock(
-            returncode=1, stderr="received unexpected HTTP status: 500 Internal Server Error", stdout=""
+            returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"
         )
         with (
             patch("devx.tools.build_image.subprocess.run", return_value=mock_result),
@@ -313,7 +313,7 @@ class TestPushImage:
             assert push_image(spec, "git.example.com", username="user", token="tok") is False
             mock_del.assert_not_called()
 
-    def test_run_push_raises_on_500(self) -> None:
+    def test_run_push_raises_on_500_stderr(self) -> None:
         """_run_push raises PushHTTP500Error when stderr contains 500."""
         from devx.tools.build_image import _run_push
 
@@ -322,6 +322,17 @@ class TestPushImage:
             with pytest.raises(PushHTTP500Error, match="HTTP 500"):
                 _run_push(["docker", "push", "img:latest"])
 
+    def test_run_push_raises_on_500_stdout(self) -> None:
+        """_run_push raises PushHTTP500Error when stdout contains 500 (docker sends to stdout)."""
+        from devx.tools.build_image import _run_push
+
+        mock_result = MagicMock(
+            returncode=1, stderr="", stdout="received unexpected HTTP status: 500 Internal Server Error"
+        )
+        with patch("devx.tools.build_image.subprocess.run", return_value=mock_result):
+            with pytest.raises(PushHTTP500Error, match="500"):
+                _run_push(["docker", "push", "img:latest"])
+
     def test_run_push_no_raise_on_non_500(self) -> None:
         """_run_push returns result when stderr has no 500."""
         from devx.tools.build_image import _run_push