chore(api): surface pyrefly output on type-check failures (#37934)

api/tests/unit_tests/libs/test_pyrefly_diagnostics.py

@@ -1,4 +1,4 @@
-from libs.pyrefly_diagnostics import extract_diagnostics
+from libs.pyrefly_diagnostics import extract_diagnostics, render_diagnostics
 
 
 def test_extract_diagnostics_keeps_only_summary_and_location_lines() -> None:
@@ -40,6 +40,37 @@ def test_extract_diagnostics_handles_error_without_location_line() -> None:
     assert diagnostics == "ERROR unexpected pyrefly output format [bad-format]\n"
 
 
+def test_extract_diagnostics_keeps_warn_headlines_and_location_lines() -> None:
+    # Arrange
+    raw_output = """INFO Checking project configured at `/tmp/project/pyrefly.toml`
+WARN Skipping include pattern `/tmp/project/tests` because it is matched by `project-excludes`.
+   --> tests/test_containers_integration_tests/pyrefly.toml:3:1
+"""
+
+    # Act
+    diagnostics = extract_diagnostics(raw_output)
+
+    # Assert
+    assert diagnostics == (
+        "WARN Skipping include pattern `/tmp/project/tests` because it is matched by `project-excludes`.\n"
+        "   --> tests/test_containers_integration_tests/pyrefly.toml:3:1\n"
+    )
+
+
+def test_render_diagnostics_falls_back_to_raw_output_for_nonzero_exit_without_matches() -> None:
+    # Arrange
+    raw_output = (
+        "INFO Checking project configured at `/tmp/project/pyrefly.toml`\n"
+        "No Python files matched pattern `/tmp/project/tests/test_containers_integration_tests`\n"
+    )
+
+    # Act
+    diagnostics = render_diagnostics(raw_output, exit_code=1)
+
+    # Assert
+    assert diagnostics == raw_output
+
+
 def test_extract_diagnostics_returns_empty_for_non_error_output() -> None:
     # Arrange
     raw_output = "INFO Checking project configured at `/tmp/project/pyrefly.toml`\n"