fix(jest-config): accept snapshotFormat.compareKeys option

[Andarist]

The configuration docs states that:

snapshotFormat [object]
[...]
Allows overriding specific snapshot formatting options documented in the pretty-format readme. For example, this config would have the snapshot formatter not print a prefix for "Object" and "Array":

However, I've found out that it's not possible to configure snapshotFormat.compareKeys from within jest.config.js file.

The reason behind this is that you are outsourcing correct types for options to the DEFAULT_OPTIONS from the pretty-format that are declared here:
https://github.com/facebook/jest/blob/c8a84566be774a35a56c26a4595c553df5fc6fc1/packages/pretty-format/src/index.ts#L401
and this is used during validation. But the correct type for snapshotFormat.compareKeys doesn't match the typeof DEFAULT_OPTIONS.compareKeys.

[Andarist]

Am I proud of this fix? No.
Does it work? Yes.

I'm afraid that I won't have time to work on the improved fix though - this is somewhat problematic because this thing is handled through a very generic validation function and this case here is very specific.

If you have any suggestions on the improved design that could be implemented quickly I could take a stab at this but I'm worried that an improved architecture around this might not be a change for a couple of lines of code.

[Andarist]

Probably the long-run plan is to use recently added schemas for validation purposes? This would IMHO go outside of the scope of this PR as it's a bigger refactor.

[SimenB]

Probably the long-run plan is to use recently added schemas for validation purposes?

Correct 🙂

[Andarist]

Those casts could be removed with such a patch:

diff --git a/packages/jest-config/src/ValidConfig.ts b/packages/jest-config/src/ValidConfig.ts
index db7ea5fe6d..1a4348d5dc 100644
--- a/packages/jest-config/src/ValidConfig.ts
+++ b/packages/jest-config/src/ValidConfig.ts
@@ -5,7 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {SnapshotFormat} from '@jest/schemas';
 import type {Config} from '@jest/types';
 import {replacePathSepForRegex} from 'jest-regex-util';
 import {multipleValidOptions} from 'jest-validate';
@@ -113,8 +112,8 @@ const initialOptions: Config.InitialOptions = {
   slowTestThreshold: 5,
   snapshotFormat: {
     ...PRETTY_FORMAT_DEFAULTS,
-    compareKeys: () => {},
-  } as SnapshotFormat,
+    compareKeys: () => 0,
+  },
   snapshotResolver: '<rootDir>/snapshotResolver.js',
   snapshotSerializers: ['my-serializer-module'],
   testEnvironment: 'jest-environment-node',
diff --git a/packages/jest-config/src/__tests__/normalize.test.ts b/packages/jest-config/src/__tests__/normalize.test.ts
index fb229b4e33..7b858656ee 100644
--- a/packages/jest-config/src/__tests__/normalize.test.ts
+++ b/packages/jest-config/src/__tests__/normalize.test.ts
@@ -9,7 +9,6 @@
 import {createHash} from 'crypto';
 import path from 'path';
 import semver = require('semver');
-import type {SnapshotFormat} from '@jest/schemas';
 import type {Config} from '@jest/types';
 import {escapeStrForRegex} from 'jest-regex-util';
 import Defaults from '../Defaults';
@@ -1928,11 +1927,11 @@ describe('snapshotFormat', () => {
       {
         ci: false,
         rootDir: '/root/',
-        snapshotFormat: {compareKeys} as SnapshotFormat,
+        snapshotFormat: {compareKeys},
       },
       {} as Config.Argv,
     );
 
-    expect((options.snapshotFormat as any).compareKeys).toBe(compareKeys);
+    expect(options.snapshotFormat.compareKeys).toBe(compareKeys);
   });
 });
diff --git a/packages/jest-schemas/src/index.ts b/packages/jest-schemas/src/index.ts
index b3f0a32eeb..09a31cff5b 100644
--- a/packages/jest-schemas/src/index.ts
+++ b/packages/jest-schemas/src/index.ts
@@ -10,6 +10,9 @@ import {Static, Type} from '@sinclair/typebox';
 const RawSnapshotFormat = Type.Partial(
   Type.Object({
     callToJSON: Type.Readonly(Type.Boolean()),
+    compareKeys: Type.Readonly(
+      Type.Function([Type.String(), Type.String()], Type.Number()),
+    ),
     escapeRegex: Type.Readonly(Type.Boolean()),
     escapeString: Type.Readonly(Type.Boolean()),
     highlight: Type.Readonly(Type.Boolean()),

But I'm not sure if I should apply it because it feels like maybe compareKeys was omitted intentionally when declaring schemas in #12384

[SimenB]

This won't actually works as we serialize the options so we can pass them to workers/child processes. So functions won't survive. (it should work when running in band, but not in other cases).

If we are to support compareKeys (and plugins) it need to point to a file that exports a function.

---

We should update the docs in the meantime so they reflect reality

[Andarist]

Oh, that makes total sense and might explain some weirdness that I've experienced 🙈

In fact... I don't even need this because my use case is simpler. I'd just like to disable the sorting of the property keys. It's important for me to verify the order of the keys because we are creating snapshots of the package.json#exports and the order within it is very important (those conditions/paths etc are matched from the top to the bottom). Would you perhaps be open to introducing a new option to the pretty-format that would just disable sorting? This way I could configure it with a simple, serializable, boolean.

A sideways note is that... while I've initially attempted to configure this the whole thing has crashed in a not very DX-friendly way. undefined got its way as value here:
https://github.com/facebook/jest/blob/c8a84566be774a35a56c26a4595c553df5fc6fc1/packages/jest-validate/src/utils.ts#L25
and crashed the runtime.

[SimenB]

Pushed 6baf127 correcting the docs.

---

Would you perhaps be open to introducing a new option to the pretty-format that would just disable sorting?

Sure. I think I'd prefer overloading the existent function parameter, tho. E.g. supporting some magic string (alphabetical, none) from config. Then pretty-format itself can in addition support a function.

[codecov-commenter]

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@@           Coverage Diff           @@
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