Purpose

Unit Test Coverage shows a percentage of a source code covered by unit tests. It is a mix of Line coverage and Condition coverage. The metric can be also calculated for a new code only.

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Unit Test Coverage may be a guide for indicating a lack of coverage via Automated Testing - just because Unit Testing is the essential part of the Testing Pyramid. A trend helps to understand how a coverage is changing over time, if it is actually growing or falling and how those trends correlate with plans/investments about appropriate development efforts related to Unit Tests. Lack of coverage is typically a key obstacle for implementing the Continuous Integration and Continuous Delivery  (CI/CD) on a project.

Metric:

• shows a percentage of a source code covered by unit tests
• shows quality of application
• shows quality of testing
• shows how the project is ready for implementation of CI/CD
• shows if the projects meets the industry quality standards
• highlights the risk of bugs being detected at a later stage of development
• helps to understand how much of your source is tested
• shows the quality of test suite

How metric works

Chart overview

Chart shows Unit Tests Coverage in %:

TOP-5 problems metric identifies 

1. No focus on quality of software
2. Quality Debt / Tech Debt / EngX processes are not included into delivery
3. There is no Test Plan and/or Strategy
4. Too many defects are found during manual and / or automated testing
5. Team misbalance (skills ratio)

Calculation

Unit Test Coverage = (CT + CF + LC) / (2*B + EL),

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