Testing.md

For what?

• Find defects
• Check for right working
• Convince customer
• For yourself

Testing ideology

1. Early tests save money
2. Excess testing does't exist
   • Избыточного тестирования не существует
   • Testing Sum(a, b): tested on (5, 4). (1, 2), (100, 500) is cringe
3. Testing shows presence of defects, not their absence
4. "80/20" rule
   • 20% of code contains 80% of errors
5. Old tests can't help in finding new mistakes
6. Testing depends on context
7. Absence of mistakes is delusion

Testings

1. Unit tests
   • For components
2. Integration tests
   • For checking component integration
3. System tests
   • Checking integration of all components (system test)
4. Acceptance testing
   • Difference with system tests: different aspects

Types of testings

• Loading testing
  • Checkout system overloading
• Stress testing
  • How long system can stay alive
• Scalability tests
  • How system works with scaling
  • Vertical scaling: improve system
  • Horizontal scaling: buy more system units
• "White box" testing
  • We know about system's structure
  • There is also "black box" testing
    • We don't know about system's structure
  1. Execution tests
  2. Mutation tests
     • Testing of tests
  3. Static tests
     • Ex: code review, linters: clang_tidy, clang_format
• Code coverage
  • gcov & lcov
  1. Statement coverage
     • void f(int a, int b) { int res = a + b; if (res < 0) { cout << res; } else { cout << -res; } }
     • Calls only f(2, 3). Covered +- 70%
  2. Branch coverage
  3. Decision coverage
     • a = -3, b = -3
     • if (a > 0 && b < 0)
     • DC is 50% because of lazy calculation
  4. Path coverage
     • Checkout full path (combinations of branches)
     • exp(if_count)

Google tests

Link