Refactor tests (#18743)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

CONTRIBUTING.md

@@ -45,11 +45,33 @@ function runFormatTest(
 ): void;
 ```
 
-Parameters:
+### **`fixtures`**
 
-- **`fixtures`**: Must be set to `import.meta` or to an object of the shape `{ importMeta: import.meta, ... }`. The object may have the `snippets` property to specify an array of extra input entries in addition to the files in the current directory. For each input entry (a file or a snippet), `runFormatTest` configures and runs a number of tests. The main check is that for a given input the output should match the snapshot (for snippets, the expected output can also be specified directly). [Additional checks](#deeper-testing) are controlled by options and environment variables.
-- **`parsers`**: A list of parser names. The tests verify that the parsers in this list produce the same output. If the list includes `typescript`, then `babel-ts`, and `oxc-ts` are included implicitly. If the list includes `flow`, then `hermes` is included implicitly. If the list includes `babel`, and the current directory is inside `tests/format/js` or `tests/format/jsx`, then `acorn`, `espree`, `meriyah`, and `oxc` are included implicitly.
-- **`options`**: In addition to Prettier's formatting options, can contain the `errors` property to specify that it's expected that the formatting shouldn't be successful and an error should be thrown for all (`errors: true`) or some combinations of input entries and parsers.
+Must be set to `import.meta` or to an object of the shape `{ importMeta: import.meta, ... }`.
+
+The object may have the `snippets` property to specify an array of extra input entries in addition to the files in the current directory.
+
+For each input entry (a file or a snippet), `runFormatTest` configures and runs a number of tests.
+
+The main check is that for a given input the output should match the snapshot (for snippets, the expected output can also be specified directly).
+
+[Additional checks](#deeper-testing) are controlled by options and environment variables.
+
+### **`parsers`**
+
+A list of parser names.
+
+The tests verify that the parsers in this list produce the same output.
+
+If the list includes `typescript`, then `babel-ts`, and `oxc-ts` are included implicitly.
+
+If the list includes `flow`, then `hermes` is included implicitly.
+
+If the list includes `babel`, and the current directory is inside `tests/format/js` or `tests/format/jsx`, then `acorn`, `espree`, `meriyah`, and `oxc` are included implicitly.
+
+### **`options`**
+
+In addition to Prettier's formatting options, can contain the `errors` property to specify that it's expected that the formatting shouldn't be successful and an error should be thrown for all (`errors: true`) or some combinations of input entries and parsers.
 
 The implementation of `runFormatTest` can be found in [`tests/config/run-format-test.js`](tests/config/run-format-test.js).