theme: Next, 3

Testing Overview

MSSE 2017

Basic Concept

• Write code to verify system
• Automatable
• Multiple levels:
  • Unit
  • Integration
  • Functional
  • Smoke/End-to-end

Rationale

• Code not done until tested
• Find mistakes sooner
• Refactor without regression
• Can help improve design
• Many, many more…

Testing strategies

• TLD (Test last development)
• TDD (Test driven development)
• BDD (Behavior driven development)
• Most important feature to have quality code coverage

Mocks

• Help isolate code under test
• Replace system component or external system with a fake
• Provide expected responses or exceptions
• Can be used to verify call sequences

Unit Testing

• Tests at the class or method level
• External system components are mocked out
• Fastest to run

Integration Testing

• Purpose: Tests the interaction of system components
• Can often include testing of
  • Data Access
  • Dependency injection

Functional Testing

• Purpose: Test a complete functional unit of a system
• System is deployed and invoked in a running environment
• Mock out external systems

Smoke Testing

• Purpose: major functions of the system are operational
• Tests end-to-end functionality
  • Including integrations with external systems
• Can be used to verify a deployment

Code Coverage

• Metrics on how much of your code is covered by your tests
• Tools can instrument your code to monitor line coverage
• Intellij provides it
• Many opinons on good coverage percentage

JaCoCo

• Popular test coverage tool
• Provides coverage reports on every build (build/reports/jacoco)

Add to build.gradle:

apply plugin: 'jacoco'

check.dependsOn jacocoTestReport

Unit Testing Frameworks

• Provide test and assertion classes
• Test run harness
• Provide pass/failure reporting functionality
• Exist for all platforms
  • Objective C, .NET, Java, Javascript, etc

JUnit

• Created by Kent Beck (original founder of Agile)
• Oldest, most-widely used Java unit test framework
• Uses approach of annotating classes and methods to mark as tests
• Great integration with most Java IDEs

Do’s

• Cover edge cases and pathological situations
• When a bug is found, write a test that exposes it
• Cleanup system (data, files) after test completes
• Tests should pass if run in any order
• Favor black-box tests
• Always have functional tests

Don’ts

• Use print statements in tests as verification
• Ignore tests that fail intermittently
• Assume environment has been setup externally
• Test setup should put system into proper state