Test Runner: custom parser for snapshot

[axetroy]

What is the problem this feature will solve?

Currently, snapshots have a special format and appear to be cjs modules

It is very convenient for snapshot parsing, but it is not suitable for human reading. It does not highlight.

I would like to have a way to customize the snapshot, since I prefer .snapshot.md to .snapshot format.

What is the feature you are proposing to solve the problem?

Add a custom parse to custom snapshot's format.

Definition:

declare module "snapshot" {
  /**
   * Sets the snapshot parser to be used for parsing and taking snapshots.
   * @param parser
   */
  export function setSnapshotParser(parser: SnapshotParser): void;

  /**
   * Interface representing a snapshot parser.
   */
  interface SnapshotParser {
    /**
     * Resolve the path to the snapshot file.
     * @param filePath
     */
    resolve(filePath: string): string;

    /**
     * Parses a snapshot file and returns its contents as a Map.
     * @param snapshotFilePath - The path to the snapshot file.
     * @returns The parsed snapshot as a Map.
     */
    parse(snapshotFilePath: string): Map<string, string>;

    /**
     * Takes a snapshot of the given value and saves it to the specified file.
     * @param value
     */
    snapshot(value: unknown): void;
  }
}

Usage:

In this example, we use custom markdown as a snapshot

snapshot.setSnapshotParser({
	// ✅ Use the markdown format for snapshots
	resolve: (filePath: string) => {
		return filePath + '.snapshot.md'
	},
	// ✅ Parse the snapshot file and return its contents as a Map
	parse: (snapshotFilePath: string) => {
		// Implement your parsing logic here
		return new Map<string, string>()
	},
	// ✅ Take a snapshot of the given value and save it to the specified file
	snapshot: (value: unknown) => {
		// Implement your snapshot logic here
	}
})

What alternatives have you considered?

No response

[cjihrig]

You can already customize how snapshots are serialized by default, as well as per call. You can also customize where the snapshots are written. There is also the fileSnapshot() API.

I'm not sure we need much more customization than that. If so, you can also register your own snapshot assertions.