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Testing English Text Normalization Components in OpenAI Whisper

This test suite validates the text normalization functionality in Whisper’s English language processing, focusing on number formatting, spelling standardization, and text normalization rules.

Test Coverage Overview

The test suite provides comprehensive coverage of English text normalization features:

Number conversion (words to digits)
Currency formatting and conversions
Ordinal number handling
Date formatting
Decimal and percentage processing
Special number sequences (e.g., ‘007’)

Implementation Analysis

The testing approach uses pytest’s parametrize decorator to efficiently test multiple normalizer implementations against the same test cases. The tests validate both EnglishNumberNormalizer and EnglishTextNormalizer classes using identical assertions, demonstrating effective test reuse.

Each test case follows a clear pattern of input string to expected normalized output comparison.

Technical Details

Testing tools and configuration:

pytest framework for test organization
Parametrized test functions for multiple normalizer classes
Direct assertion testing for string normalization
Separate test functions for spelling and general text normalization

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Comprehensive edge case coverage
Systematic test organization by functionality
DRY principle through parametrized tests
Clear test case documentation through descriptive assertions
Isolated testing of distinct normalization features

openai/whisper

tests/test_normalizer.py

            
import pytest

from whisper.normalizers import EnglishTextNormalizer
from whisper.normalizers.english import (
    EnglishNumberNormalizer,
    EnglishSpellingNormalizer,
)


@pytest.mark.parametrize("std", [EnglishNumberNormalizer(), EnglishTextNormalizer()])
def test_number_normalizer(std):
    assert std("two") == "2"
    assert std("thirty one") == "31"
    assert std("five twenty four") == "524"
    assert std("nineteen ninety nine") == "1999"
    assert std("twenty nineteen") == "2019"

    assert std("two point five million") == "2500000"
    assert std("four point two billions") == "4200000000s"
    assert std("200 thousand") == "200000"
    assert std("200 thousand dollars") == "$200000"
    assert std("$20 million") == "$20000000"
    assert std("€52.4 million") == "€52400000"
    assert std("£77 thousands") == "£77000s"

    assert std("two double o eight") == "2008"

    assert std("three thousand twenty nine") == "3029"
    assert std("forty three thousand two hundred sixty") == "43260"
    assert std("forty three thousand two hundred and sixty") == "43260"

    assert std("nineteen fifties") == "1950s"
    assert std("thirty first") == "31st"
    assert std("thirty three thousand and three hundred and thirty third") == "33333rd"

    assert std("three billion") == "3000000000"
    assert std("millions") == "1000000s"

    assert std("july third twenty twenty") == "july 3rd 2020"
    assert std("august twenty sixth twenty twenty one") == "august 26th 2021"
    assert std("3 14") == "3 14"
    assert std("3.14") == "3.14"
    assert std("3 point 2") == "3.2"
    assert std("3 point 14") == "3.14"
    assert std("fourteen point 4") == "14.4"
    assert std("two point two five dollars") == "$2.25"
    assert std("two hundred million dollars") == "$200000000"
    assert std("$20.1 million") == "$20100000"

    assert std("ninety percent") == "90%"
    assert std("seventy six per cent") == "76%"

    assert std("double oh seven") == "007"
    assert std("double zero seven") == "007"
    assert std("nine one one") == "911"
    assert std("nine double one") == "911"
    assert std("one triple oh one") == "10001"

    assert std("two thousandth") == "2000th"
    assert std("thirty two thousandth") == "32000th"

    assert std("minus 500") == "-500"
    assert std("positive twenty thousand") == "+20000"

    assert std("two dollars and seventy cents") == "$2.70"
    assert std("3 cents") == "¢3"
    assert std("$0.36") == "¢36"
    assert std("three euros and sixty five cents") == "€3.65"

    assert std("three and a half million") == "3500000"
    assert std("forty eight and a half dollars") == "$48.5"
    assert std("b747") == "b 747"
    assert std("10 th") == "10th"
    assert std("10th") == "10th"


def test_spelling_normalizer():
    std = EnglishSpellingNormalizer()

    assert std("mobilisation") == "mobilization"
    assert std("cancelation") == "cancellation"


def test_text_normalizer():
    std = EnglishTextNormalizer()
    assert std("Let's") == "let us"
    assert std("he's like") == "he is like"
    assert std("she's been like") == "she has been like"
    assert std("10km") == "10 km"
    assert std("10mm") == "10 mm"
    assert std("RC232") == "rc 232"

    assert (
        std("Mr. Park visited Assoc. Prof. Kim Jr.")
        == "mister park visited associate professor kim junior"
    )