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C++ Testing

Testing frameworks provide assertions and test runners, but the structure of a good test is independent of GoogleTest or Catch2.

Arrange, Act, Assert

Arrange, Act, Assert (AAA) separates a test into three clear phases:

Phase Purpose
Arrange Create the inputs, initial state, and dependencies needed by the test.
Act Perform the one behavior being tested.
Assert Verify the observable result.

The test body is the same regardless of the framework; only the assertion syntax changes:

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// Arrange
Calculator calculator;

// Act
const int result = calculator.add(2, 3);

// Assert with Catch2
REQUIRE(result == 5);

// Assert with GoogleTest instead
// EXPECT_EQ(result, 5);

Assert is a test phase

The Assert phase means verifying the result. It does not specifically mean the C assert() macro or any particular testing-framework macro.

Use these rules when designing tests:

  • Test one observable behavior at a time.
  • Prefer one meaningful Act in each test.
  • Name the test after the behavior and expected outcome.
  • Test through the module's public interface, not its private implementation.

Framework-specific features such as Catch2 sections and GoogleTest fixtures belong in their respective tutorials.

Choose a framework

Choose a C++ testing framework:

GoogleTest logo

GoogleTest
Catch2 logo

Catch2

The Catch2 artwork comes from the official Catch2 repository.