如何在Apache Beam中对早期触发进行单元测试(Python SDK)

import unittest
import apache_beam as beam
from apache_beam.testing.util import assert_that
from apache_beam.testing.test_pipeline import TestPipeline

class MyPipelineTest(unittest.TestCase):
    def test_early_trigger(self):
        # 测试代码

def test_early_trigger(self):
    with TestPipeline() as p:
        # 创建测试输入数据
        input_data = ['apple', 'banana', 'cherry']
        
        # 构建管道，并对早期触发进行测试
        output = (
            p
            | beam.Create(input_data)
            | beam.Map(lambda x: x.upper())
        )
        
        # 定义期望的输出结果
        expected_output = ['APPLE', 'BANANA', 'CHERRY']
        
        # 使用PAssert进行断言
        assert_that(output, beam.equal_to(expected_output))

if __name__ == '__main__':
    unittest.main()