I’m working on testing a MongoDB aggregation in a Spring Boot service class. The test class uses Mockito to mock the aggregation operation, but I’m encountering an error when running the test. Specifically, the error message says "Aggregation pipeline must not be null.
I’m using @SpringBootTest with @MockBean to mock the MongoTemplate. I’m also using Mockito to mock the aggregate() method in the setup() method. I mock the response when mongoTemplate.aggregate(...) is called, expecting it to return a list of GridIp objects.
When running the test, the error "Aggregation pipeline must not be null" occurs, suggesting that the pipeline isn’t correctly passed in the test.
The method being tested is getAllGridIps(), which builds an aggregation pipeline using Aggregation.newAggregation(...) and then calls mongoTemplate.aggregate(...) with that pipeline.
The test is being written using JUnit, Mockito, and Spring Boot. The project uses MongoDB, and I’m mocking the MongoTemplate to test the aggregation method.
I’m trying to understand why the aggregation pipeline is being treated as null in the test, despite mocking the pipeline creation. Am I missing any annotations or configurations? Could this be an issue with how I’m setting up Mockito, or is there something else I need to mock?
What I tried:
I wrote a test using @SpringBootTest and MockitoAnnotations.openMocks(this) to mock mongoTemplate.aggregate(...). I mocked the aggregation pipeline using Aggregation.newAggregation(...) and expected it to return a mocked list of GridIp objects. I also ensured the aggregation pipeline was built properly in the service method.
What I expected
I expected the test to pass by successfully returning two GridIp objects (with titles "ip1" and "ip2") from the mocked aggregation pipeline. However, the test failed with the error "Aggregation pipeline must not be null."
getAllGridIps Method Building Aggregation Pipeline in Spring Boot Service
Test Class for Mocking MongoTemplate with Aggregation in Spring Boot
Error Log: Aggregation Pipeline Must Not Be Null in GridIp Aggregation Test
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