What is the difference between white-box, black-box, and gray-box testing?

Question

Accepted Answer

**White-Box** — full code knowledge. **Black-Box** — no code knowledge. **Gray-Box** — partial knowledge.

**White-Box Testing:**
- Full code access.
- Test internal logic.
- Code coverage analysis.
- Developer performs.

```
White-Box:
See internal code structure
Test all branches and paths
Measure code coverage
(Full knowledge)
```

**Black-Box Testing:**
- No code access.
- Test inputs/outputs.
- User perspective.
- Tester performs.

```
Black-Box:
See only inputs and outputs
Test functionality
No knowledge of implementation
(No knowledge)
```

**Gray-Box Testing:**
- Partial code access.
- Test with some knowledge.
- Integration testing.
- Best of both.

```
Gray-Box:
See database schema
Test API + database
Some internal knowledge
(Partial knowledge)
```

**Key differences:**
- **White-Box** — full knowledge.
- **Black-Box** — no knowledge.
- **Gray-Box** — partial knowledge.

Systems Analyst: What is the difference between white-box, black-box, and gray-box testing?