jestjs/jest · error · Error

${matcherHint(...)} Expected properties must be an object ${

Error message

${matcherHint(...)} Expected properties must be an object
${printWithType('Expected properties', propertiesOrSnapshot, printExpected)}

What it means

Thrown by `toMatchInlineSnapshot` (index.ts:234-249) when the call passes a `propertiesOrSnapshot` argument that is neither a string (treated as the inline snapshot) nor a non-null object (treated as expected properties). Same shape as the toMatchSnapshot guard but for inline variant.

Source

Thrown at packages/jest-snapshot/src/index.ts:238

  const length = arguments.length;
  if (length === 2 && typeof propertiesOrSnapshot === 'string') {
    inlineSnapshot = propertiesOrSnapshot;
  } else if (length >= 2) {
    const options: MatcherHintOptions = {
      isNot: this.isNot,
      promise: this.promise,
    };
    if (length === 3) {
      options.secondArgument = SNAPSHOT_ARG;
      options.secondArgumentColor = noColor;
    }

    if (
      typeof propertiesOrSnapshot !== 'object' ||
      propertiesOrSnapshot === null
    ) {
      throw new Error(
        matcherErrorMessage(
          matcherHint(matcherName, undefined, PROPERTIES_ARG, options),
          `Expected ${EXPECTED_COLOR('properties')} must be an object`,
          printWithType(
            'Expected properties',
            propertiesOrSnapshot,
            printExpected,
          ),
        ),
      );
    }

    if (length === 3 && typeof inlineSnapshot !== 'string') {
      throw new Error(
        matcherErrorMessage(
          matcherHint(matcherName, undefined, PROPERTIES_ARG, options),
          'Inline snapshot must be a string',
          printWithType('Inline snapshot', inlineSnapshot, serialize),

View on GitHub (pinned to f49721c78e)

Solutions

1. Pass an object for properties, or a backtick string for the inline snapshot.
2. If you don't want properties, drop the argument entirely so Jest writes the snapshot for you.

Example fix

// before
expect(x).toMatchInlineSnapshot(123);

// after
expect(x).toMatchInlineSnapshot(`123`);
// or, with properties:
expect(x).toMatchInlineSnapshot({ code: 123 });

if (arg != null && typeof arg !== 'object' && typeof arg !== 'string') {
  throw new Error('toMatchInlineSnapshot needs an object or string');
}
expect(x).toMatchInlineSnapshot(arg);

function isInlineSnapshotArg(v: unknown): v is object | string {
  return v == null || typeof v === 'object' || typeof v === 'string';
}

When it happens

Trigger: `expect(x).toMatchInlineSnapshot(42)`, `expect(x).toMatchInlineSnapshot(null, 'snapshot')`, or `toMatchInlineSnapshot(true)`.

Common situations: Passing a primitive where an object or template-literal string is expected. Variable mistakenly null.

Related errors

• ${matcherHint(...)} Inline snapshot must be a string ${print
• ${matcherHint(...)} Expected properties must be an object ${
• ${matcherHintFromConfig(...)} received value must be an obje
• ${matcherHint(...)} received value must be a function ${prin
• Jest: Couldn't infer stack frame for inline snapshot.

AI-assisted analysis of jestjs/jest@f49721c78e (2026-08-03). Data as JSON: /data/errors/06526f4c2164526a.json. Report an issue: GitHub.