feat(config): add `mergify config simulate` command by jd · Pull Request #1018 · Mergifyio/mergify-cli

jd · 2026-03-10T14:19:01Z

Add a simulate subcommand that sends the local Mergify configuration
to the Mergify PR simulator API, showing what actions would be triggered
for a given pull request.

Usage: mergify config simulate <PR_URL> [--config path]

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

Depends-On: #1016

jd · 2026-03-10T14:19:03Z

This pull request is part of a stack:

feat(config): add mergify config validate command (add .mergify.yml "lint" option #1010) (#1016)
feat(config): add mergify config simulate command (#1018) 👈

mergify · 2026-03-10T14:19:28Z

Copilot

Pull request overview

Adds a new mergify config simulate subcommand that posts a local .mergify.yml to the Mergify PR simulator API for a given PR URL and prints the simulator’s title/summary.

Changes:

Add config simulate <PR_URL> command with --config, --token, and --api-url options.
Add async simulator API helper (simulate_pr) plus a raw config reader.
Extend config CLI tests to cover simulate success + basic argument/file validation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
`mergify_cli/config/cli.py`	Introduces the `simulate` subcommand and PR URL parsing logic.
`mergify_cli/config/validate.py`	Adds raw config reading and the async simulator API call helper/result type.
`mergify_cli/tests/config/test_validate.py`	Adds tests for the new `simulate` command and refactors schema URL usage.

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Copilot · 2026-03-10T14:23:10Z

mergify_cli/config/validate.py

+    response = await client.post(
+        f"/v1/repos/{repository}/pulls/{pull_number}/simulator",
+        json={"mergify_yml": mergify_yml},
+    )


simulate_pr() never calls response.raise_for_status(). It currently relies on the caller to have an event hook that raises on HTTP >= 400, which makes the helper easy to misuse (and inconsistent with fetch_schema()). Call raise_for_status() before decoding JSON so errors are handled predictably regardless of client configuration.

Suggested change

)

)

response.raise_for_status()

Copilot · 2026-03-10T14:23:11Z

mergify_cli/tests/config/test_validate.py


+_SCHEMA_URL = "https://docs.mergify.com/mergify-configuration-schema.json"
+_PR_URL = "https://github.com/owner/repo/pull/42"
+_SIMULATOR_URL = "https://api.mergify.com/v1/repos/owner/repo/pulls/42/simulator"


_SIMULATOR_URL is introduced but never used in this test module. Either remove it or use it to build the respx route in test_simulate_pr() so the constant serves a purpose.

Suggested change

_SIMULATOR_URL = "https://api.mergify.com/v1/repos/owner/repo/pulls/42/simulator"

Copilot · 2026-03-10T14:23:11Z

mergify_cli/tests/config/test_validate.py

+        assert "The configuration is valid" in result.output
+        assert "No actions will be triggered" in result.output
+
+


The new simulate command tests cover success and local validation errors, but there is no coverage for simulator API failures (e.g., HTTP 4xx/5xx or network errors). Adding a test that mocks a non-2xx simulator response (and asserts a clean, non-traceback CLI error with non-zero exit) would help lock down the intended UX.

Suggested change

def test_simulate_api_failure(tmp_path: pathlib.Path) -> None:

config_path = _write_config(tmp_path, "pull_request_rules: []\n")

with respx.mock(base_url="https://api.mergify.com") as rsp:

rsp.post("/v1/repos/owner/repo/pulls/42/simulator").mock(

return_value=Response(

500,

json={

"message": "internal error",

},

),

)

result = CliRunner().invoke(

config,

[

"simulate",

_PR_URL,

"--config",

config_path,

"--token",

"test-token",

],

)

assert result.exit_code != 0

assert "Traceback" not in result.output

Copilot · 2026-03-10T14:23:11Z

mergify_cli/config/cli.py

+        result = await config_validate.simulate_pr(
+            client,
+            repository,
+            pull_number,
+            mergify_yml,
+        )


simulate() does not catch network-level httpx exceptions (e.g., DNS/connect/timeout). Those will bypass cli.main()’s HTTPStatusError handler and surface as an uncaught traceback. Mirror validate() by catching httpx.HTTPError around the simulator call and raising a click.ClickException with a user-friendly message (keeping HTTPStatusError behavior intact).

Suggested change

result = await config_validate.simulate_pr(

client,

repository,

pull_number,

mergify_yml,

)

try:

result = await config_validate.simulate_pr(

client,

repository,

pull_number,

mergify_yml,

)

except httpx.HTTPStatusError:

# Let HTTPStatusError bubble up so it can be handled by the global handler.

raise

except httpx.HTTPError as exc:

msg = f"Failed to contact Mergify API at {api_url}: {exc}"

raise click.ClickException(msg) from exc

Copilot · 2026-03-10T14:23:11Z

mergify_cli/config/cli.py

+_PR_URL_RE = re.compile(
+    r"https?://[^/]+/(?P<owner>[^/]+)/(?P<repo>[^/]+)/pull/(?P<number>\d+)",
+)
+
+
+def _parse_pr_url(url: str) -> tuple[str, int]:
+    m = _PR_URL_RE.match(url)
+    if not m:
+        msg = f"Invalid pull request URL: {url}"
+        raise click.ClickException(msg)
+    return f"{m.group('owner')}/{m.group('repo')}", int(m.group("number"))


_PR_URL_RE is not anchored to the end of the string. As written, inputs like https://github.com/org/repo/pull/42foo will be accepted and parsed as PR #42 instead of being rejected. Consider switching to fullmatch() or updating the regex to require an end delimiter (e.g., end-of-string or /, ?, #).

Add a new `config validate` subcommand that validates Mergify configuration files against the official JSON schema. Supports auto-detection of config file location and explicit path via --config. Closes #1010 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> Change-Id: Ib7a8075cd92a62a2a7d761a4eab5e309c914dd21 Claude-Session-Id: 35f710ae-3790-4349-b55b-82247979f4a8

Add a `simulate` subcommand that sends the local Mergify configuration to the Mergify PR simulator API, showing what actions would be triggered for a given pull request. Usage: mergify config simulate <PR_URL> [--config path] Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> Change-Id: I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1 Claude-Session-Id: 35f710ae-3790-4349-b55b-82247979f4a8

mergify · 2026-03-10T14:54:30Z

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jd mentioned this pull request Mar 10, 2026

feat(config): add mergify config validate command (#1010) #1016

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jd force-pushed the devs/jd/feat/config-validate/I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1 branch from 216d896 to d119bfc Compare March 10, 2026 14:26

jd force-pushed the devs/jd/feat/config-validate/Ib7a8075cd92a62a2a7d761a4eab5e309c914dd21 branch from 68e009f to 01b46c4 Compare March 10, 2026 14:26

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jd force-pushed the devs/jd/feat/config-validate/I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1 branch from d119bfc to d391491 Compare March 10, 2026 14:31

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jd force-pushed the devs/jd/feat/config-validate/I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1 branch from d391491 to a6569f3 Compare March 10, 2026 14:35

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jd force-pushed the devs/jd/feat/config-validate/Ib7a8075cd92a62a2a7d761a4eab5e309c914dd21 branch from a0412dc to be4ceb9 Compare March 10, 2026 14:39

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jd deleted the devs/jd/feat/config-validate/I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1 branch March 10, 2026 14:39

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feat(config): add `mergify config simulate` command#1018

feat(config): add `mergify config simulate` command#1018
jd wants to merge 2 commits intodevs/jd/feat/config-validate/Ib7a8075cd92a62a2a7d761a4eab5e309c914dd21from
devs/jd/feat/config-validate/I5246a6407b4c3a7aa38dfa8b963bae3bf016a8e1

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		assert "The configuration is valid" in result.output
		assert "No actions will be triggered" in result.output

+def test_simulate_api_failure(tmp_path: pathlib.Path) -> None:
+    config_path = _write_config(tmp_path, "pull_request_rules: []\n")
+    with respx.mock(base_url="https://api.mergify.com") as rsp:
+        rsp.post("/v1/repos/owner/repo/pulls/42/simulator").mock(
+            return_value=Response(
+,
+                json={
+                    "message": "internal error",
+                },
+            ),
+        )
+        result = CliRunner().invoke(
+            config,
+            [
+                "simulate",
+                _PR_URL,
+                "--config",
+                config_path,
+                "--token",
+                "test-token",
+            ],
+        )
+        assert result.exit_code != 0
+        assert "Traceback" not in result.output

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