_equals(
            firstMismatchIndex,
            -1,
            firstMismatchIndex === -1
                ? 'WaveShaperNode output should match the spec.'
                : `Mismatch at sample ${firstMismatchIndex}: ` +
                    `actual = ${actual}, expected = ${expected}, ` +
                    `tolerance = ${tolerance}`);
      }

      promise_test(async t => {
        // Create offline audio context.
        context = new OfflineAudioContext(1, numberOfRenderFrames, sampleRate);

      