# golden
<!-- status autogenerated section -->
| Status        |           |
| ------------- |-----------|
| Stability     | [alpha]: traces, metrics, logs   |
| Issues        | [![Open issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aopen%20label%3Apkg%2Fgolden%20&label=open&color=orange&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aopen+is%3Aissue+label%3Apkg%2Fgolden) [![Closed issues](https://img.shields.io/github/issues-search/open-telemetry/opentelemetry-collector-contrib?query=is%3Aissue%20is%3Aclosed%20label%3Apkg%2Fgolden%20&label=closed&color=blue&logo=opentelemetry)](https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aclosed+is%3Aissue+label%3Apkg%2Fgolden) |
| [Code Owners](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/CONTRIBUTING.md#becoming-a-code-owner)    | [@djaglowski](https://www.github.com/djaglowski), [@atoulme](https://www.github.com/atoulme) |

[alpha]: https://github.com/open-telemetry/opentelemetry-collector#alpha
<!-- end autogenerated section -->

The package golden provides utilities for reading and writing files with metrics, traces and logs in YAML format. 
The package is expected to be used with pkg/pdatatest module.

## Generating an expected result file

The easiest way to capture the expected result in a file is `golden.WriteMetrics` or `golden.WriteLogs`.

When writing a new test:
1. Write the test as if the expected file exists.
2. Follow the steps below for updating an existing test.

When updating an existing test:
1. Add a call to `golden.WriteMetrics` or `golden.WriteLogs` or in the appropriate place.
2. Run the test once.
3. Remove the call to `golden.WriteMetrics` or `golden.WriteLogs`.

NOTE: `golden.WriteMetrics` will always mark the test as failed. This behavior is
necessary to ensure the function is removed after the golden file is written.

```go
func TestScraper(t *testing.T) {
	cfg := createDefaultConfig().(*Config)
	require.NoError(t, component.ValidateConfig(cfg))

	scraper := newScraper(componenttest.NewNopReceiverCreateSettings(), cfg)

	err := scraper.start(context.Background(), componenttest.NewNopHost())
	require.NoError(t, err)

	actualMetrics, err := scraper.scrape(context.Background())
	require.NoError(t, err)

	expectedFile := filepath.Join("testdata", "scraper", "expected.yaml")

	golden.WriteMetrics(t, expectedFile, actualMetrics) // This line is temporary! TODO remove this!!

	expectedMetrics, err := golden.ReadMetrics(expectedFile)
	require.NoError(t, err)

	require.NoError(t, pmetrictest.CompareMetrics(expectedMetrics, actualMetrics))
}
```