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80 lines
2.3 KiB
Markdown
80 lines
2.3 KiB
Markdown
---
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title: Unit testing
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---
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# Unit testing
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- divide code into units ⇒ test those units
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- consider appropriate scale
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- depends on type of code project as well as language
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- object oriented: classes? methods?
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- procedural: functions? modules?
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- test each unit independently
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- frequently
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- often after each commit/push
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- can run tests if parallel
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- may need to build environment in which tests run
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### 0.1 supports useful principles
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can support complementary work by team members
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early discovery of problems
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can help with documentation and specification
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- unit tests can be a form of executable specification
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- helps team members understand requirements
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### 0.2 Test environment
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consider code that interacts with a database
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- you cant let that code write to a real database
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- but you want to check that writes were performed
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common solution is to create a fake database
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- class that mocs database operations
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- can also test error handling by returning error codes
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mock up the database with a pretend model that returns fixed results to query
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- be careful not to mock up data base incorrectly
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can be a pre-recorded interaction
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### 0.3 Test life cycle
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- set up test environment
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- run test code
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- check results
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- aggregate results into test summary
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simple test: run method ⇒ check value
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tests may chack that code fails appropriately
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- crash when expected
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- exceptions are generated
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### 0.4 Language support
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language may have bilt in testing support
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- e.g., Go and Rust have command line tools to run tests
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External tools can often work well too
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- e.g., java code annotations can mark tests
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- java ignores most annotations, but testing tools (JUnit) can use them
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- annotations are symbols that begin with @ in source code
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we want to distinguish between tests and normal code
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- also should support for sqapping in/out mocking code
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### 0.5 JUnit
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test classes have a particular filename pattern
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annotate test methods with @Test
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other annotations
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- @BeforeAll and @BeforeEach (and after)
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- @RepeatedTest
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JUnit 5 also supports dynamically generated tests
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### 0.6 TestNG
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based off JUnit and fixes some it it's problems
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- provides control over threading
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- run tests in parallel
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- also tests for parallelism bugs
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- multithreaded code i hard to debug
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- data driven testing
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- also
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- integration testing
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- end to end testing |