Condition Coverage in Software Testing

When writing test cases, it’s not enough to check just a few paths through the code you need to make sure every condition in your logic is tested. Condition Coverage (also known as Predicate Coverage) is a popular white-box testing technique that measures whether all possible conditions in decision statements have been executed.

In this article, we’ll explore what Condition Coverage is, how it works, why it’s important, with practical examples to make it easy for beginners.

What is Condition Coverage?

Condition Coverage ensures that every individual condition in a decision statement (such as an if, else if, or logical operators like AND/OR) is tested at least once with both true and false outcomes.

This means that instead of just testing the overall branch, you test each condition independently.
Formula for Condition Coverage:

Condition Coverage (%) = (Number of executed conditions / Total number of conditions) * 100

So, if you have 4 conditions in your code, and your tests execute 3 of them, your coverage is 75%.

Example of Condition Coverage

Let’s understand this with a simple function:

javascript
function checkNumberSign(number) {
    let result;

    if (number > 0) {
        result = "Positive";
    } else if (number < 0) {
        result = "Negative";
    } else {
        result = "Zero";
    }

    return result;
}

Here we have 3 conditions:

1. number > 0 → Positive

2. number < 0 → Negative

3. number === 0 → Zero

To achieve 100% Condition Coverage, your test cases must include:

• A positive number → covers number > 0

• A negative number → covers number < 0

• Zero → covers number === 0

This ensures every possible outcome of the conditions is tested.

How Does Condition Coverage Work?

Here’s how it works step by step:

1. Identify decision points – Look for if, else if, or logical operators in the code.

2. Break conditions into parts – If you have if (A && B), you need to test A and B separately.

3. Design test cases – Create tests where each condition evaluates to both true and false.

4. Run tests – Execute your test suite against the code.

5. Generate coverage report – Tools like Jest (JavaScript), PyTest (Python), or JUnit (Java) can show which conditions are covered.

Benefits of Condition Coverage

• Thorough testing – Ensures every logical condition has been tested.

• Early bug detection – Helps catch hidden edge cases.

• Improved reliability – Makes software more stable by covering all decision outcomes.

• Better maintainability – Well-tested code is easier to change and extend.

• Higher quality assurance – Reduces risk of missed scenarios.

Example Test Cases for Condition Coverage

Let’s create test cases for the checkNumberSign function:

javascript
console.log(checkNumberSign(10));   // Positive
console.log(checkNumberSign(-5));   // Negative
console.log(checkNumberSign(0));    // Zero

These 3 test cases ensure 100% condition coverage because each possible outcome of the conditions is executed.

How to Calculate the Coverage using Keploy?

If you’re a developer, you probably care about statement and branch coverage — Keploy calculates that for you.

If you’re a QA, you focus more on API schema and business use‑case coverage — Keploy calculates that too. This way coverage isn’t subjective anymore.

Expand API Coverage using AI

Keploy uses existing recordings, Swagger/OpenAPI Schema to find: boundary values, missing/extra fields, wrong types, out‑of‑order sequences, retries/timeouts.

This helps expand API Schema, Statement, and Branch Coverage.

Conclusion

Condition Coverage is one of the most important testing techniques for ensuring code quality. By testing each condition in decision statements individually, it helps developers catch hidden bugs early and makes applications more reliable.

If you’re just starting with software testing, try applying it in your next project. It’s a simple yet powerful way to build confidence in your test suite and deliver more robust software.

FAQs:

Q1. What is the difference between Branch Coverage and Condition Coverage?

Branch Coverage checks whether all possible paths (if / else) are tested, while Condition Coverage ensures that each condition within a decision (true/false) is tested.

Q2. Why is Condition Coverage important in software testing?

It ensures all logical conditions are tested, helping detect hidden bugs and making the code more reliable.

Q3. Can Condition Coverage guarantee bug-free software?

No, but it significantly reduces the chances of missing logical errors by thoroughly testing conditions.

Q4. Which tools can I use to measure Condition Coverage?

Popular tools include Jest (JavaScript), PyTest (Python), JUnit (Java), JaCoCo, and Cobertura.

Q5. How do I achieve 100% Condition Coverage?

Write test cases for each condition in your code so that both true and false outcomes are tested at least once.