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+- Author: Xuanwo <github@xuanwo.io>
+- Start Date: 2021-07-07
+- RFC PR: [beyondstorage/specs#137](https://github.com/beyondstorage/specs/issues/137)
+- Tracking Issue: [beyondstorage/go-storage#0](https://github.com/beyondstorage/go-storage/issues/0)
+
+# GSP-137: Service Output Template
+
+## Background
+
+[Increase code coverage](https://github.com/beyondstorage/go-storage/issues/620) plans to move `cmd/definitions/tests` into `tests` and support generating files into `generate_test.go` so we won't export test services.
+
+So `definitions` should have the ability to generate all files into a specified output filename template.
+
+## Proposal
+
+I propose to add a new field `output_template` in `service.toml`. In `output_template`, we will use format string like `%s_test.go`.
+
+If service provider specify `output_template` to `%s_test.go`, `definitions` will generate files into:
+
+- `generated_test.go`
+- `service_test.go`
+- `storage_test.go`
+
+## Rationale
+
+N/A
+
+## Compatibility
+
+This GSP introduces a compatible change.
+
+## Implementation
+
+- Add `output_template` field in specs.
+- Support `output_template` in go-storage.