Function reduceBadExampleSize

tools/code-sample-minimizer.js:44–298

* Given "bad" source text (e.g. an code sample that causes a rule to crash), tries to return a smaller * piece of source text which is also "bad", to make it easier for a human to figure out where the * problem is. * @param {Object} options Options to process * @param {string} options.sourceText

({
	sourceText,
	predicate,
	parser = {
		parse: (code, options) =>
			espree.parse(code, {
				...options,
				loc: true,
				range: true,
				raw: true,
				tokens: true,
				comment: true,
				eslintVisitorKeys: true,
				eslintScopeManager: true,
				ecmaVersion: espree.latestEcmaVersion,
				sourceType: "script",
			}),
	},
	visitorKeys = evk.KEYS,
})

 * @returns {string} Another piece of "bad" source text, which may or may not be smaller than the original source text.
 */
function reduceBadExampleSize({
	sourceText,
	predicate,
	parser = {
		parse: (code, options) =>
			espree.parse(code, {
				...options,
				loc: true,
				range: true,
				raw: true,
				tokens: true,
				comment: true,
				eslintVisitorKeys: true,
				eslintScopeManager: true,
				ecmaVersion: espree.latestEcmaVersion,
				sourceType: "script",
			}),
	},
	visitorKeys = evk.KEYS,
}) {
	let counter = 0;

	/**
	 * Returns a new unique identifier
	 * @returns {string} A name for a new identifier
	 */
	function generateNewIdentifierName() {
		return `$${counter++}`;
	}

	/**
	 * Determines whether a source text sample is "bad"
	 * @param {string} updatedSourceText The sample
	 * @returns {boolean} `true` if the sample is "bad"
	 */
	function reproducesBadCase(updatedSourceText) {
		try {
			parser.parse(updatedSourceText);
		} catch {
			return false;
		}

		return predicate(updatedSourceText);
	}

	assert(
		reproducesBadCase(sourceText),
		"Original source text should reproduce issue",
	);
	const ast = parser.parse(sourceText);

	/*
	 * Track committed source-text modifications as { start, end, replacement } objects.
	 * All modifications are non-overlapping — the algorithm only modifies a subtree after
	 * deciding not to remove its ancestor, so ranges at different recursion levels are disjoint.
	 */
	const modifications = [];