Contents
Testing in Go
Syntax
Testing is a critical part of software development, ensuring that your code functions correctly and efficiently. Go provides built-in support for writing tests, including table-driven tests and benchmarks, as well as tools for measuring test coverage. Let’s explore these features and see how they can help you maintain high-quality Go code.
Writing Tests
Go uses a simple approach to testing through its testing package. Test files should have a _test.go suffix and test functions should start with Test.
Basic Test Example
Here’s a basic example of a test in Go:
// mathutil.go
package mathutil
// Add adds two integers and returns the result.
func Add(a, b int) int {
return a + b
}
// mathutil_test.go
package mathutil
import "testing"
// TestAdd tests the Add function.
func TestAdd(t *testing.T) {
result := Add(2, 3)
expected := 5
if result != expected {
t.Errorf("Add(2, 3) = %d; want %d", result, expected)
}
}
To run the tests, use the command:
go test
Table-Driven Tests
Table-driven tests are a pattern in Go for testing multiple cases with different inputs and expected outputs. This approach makes it easy to manage multiple test scenarios in a concise format.
Table-Driven Test Example
Let’s expand on the Add function with a table-driven test:
// mathutil_test.go
package mathutil
import "testing"
// TestAdd tests the Add function using a table-driven approach.
func TestAdd(t *testing.T) {
tests := []struct {
name string
a, b int
expected int
}{
{"Add positive numbers", 2, 3, 5},
{"Add zero", 0, 5, 5},
{"Add negative numbers", -1, -2, -3},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
result := Add(tt.a, tt.b)
if result != tt.expected {
t.Errorf("Add(%d, %d) = %d; want %d", tt.a, tt.b, result, tt.expected)
}
})
}
}
Benchmarking
Benchmarking is used to measure the performance of your code. Go’s testing framework supports benchmarks using functions that start with Benchmark.
Benchmark Example
Here’s how you can write a benchmark for the Add function:
// mathutil_test.go
package mathutil
import "testing"
// BenchmarkAdd measures the performance of the Add function.
func BenchmarkAdd(b *testing.B) {
for i := 0; i < b.N; i++ {
Add(2, 3)
}
}
Run benchmarks with the command:
go test -bench=.
Coverage
Coverage analysis helps determine which parts of your code are exercised by tests. Go provides a way to measure test coverage with the -cover flag.
Checking Test Coverage
To check coverage, use:
go test -cover
For a detailed report, use:
go test -coverprofile=coverage.out
go tool cover -html=coverage.out