Excluding Test Files from Code Coverage with c8
Problem: You're using c8 for code coverage analysis in your JavaScript project. But, you want to exclude test files like those ending with *.spec.mjs from the coverage report because they aren't part of the production code.
Solution: c8 provides powerful configuration options to customize how it analyzes your code. To exclude test files, you can modify your c8 configuration using a .c8rc file.
Scenario and Code:
Let's imagine you have a project structure like this:
my-project
├── src
│ └── myModule.mjs
└── test
└── myModule.spec.mjs
Your myModule.mjs file is the production code you want to analyze for coverage, while myModule.spec.mjs is your test file. You can use a .c8rc file to exclude the test file from coverage.
Example .c8rc configuration:
{
"exclude": [
"**/test/**/*.mjs",
"**/__tests__/**/*.js"
]
}
Explanation:
exclude: This property defines patterns for files and directories to exclude from coverage analysis.**/test/**/*.mjs: This pattern matches all*.mjsfiles within thetestdirectory and its subdirectories, effectively excluding all test files from coverage.**/__tests__/**/*.js: This pattern excludes files within a common__tests__directory, if you happen to use that for your tests.
Additional Insights:
- Pattern Flexibility: You can use various wildcards and regular expressions to define your exclusion patterns. Refer to c8's documentation for details.
includeProperty: Whileexcludeis the most common approach, you can also use theincludeproperty in your.c8rcto specify only the files you want to include in coverage analysis.- Coverage Tools: Consider using a dedicated coverage reporting tool like
nycoristanbulalongside c8 for enhanced reporting and visualization.
Conclusion:
Excluding test files from your code coverage analysis is essential for accurate and meaningful results. By using the exclude property in your .c8rc configuration, you can fine-tune c8's behavior and focus on coverage metrics for your production code.
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