Go Common Test

January 22, 2025 · 2 min read · Page View:

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The test methods in Go mainly include three types: unit test, benchmark test, and example test.

First of all:

1. You should import the testing package first.
2. In the package directory, all source code files with the suffix *_test.go are part of the go test test, and will not be compiled into the final executable file by go build.

Unit Test #

The basic format/signature is:

func TestXxx(t *testing.T) {
    // ...
}

Put the _test.go and .go in the same dir, and run go test -v to execute the test detailed, the go test -cover to check the coverage of the test.

Benchmark test #

The benchmark test will not be excuted by default, you need to use go test -bench=Xxx to execute the benchmark test.

The basic format/signature is:

func BenchmarkXxx(b *testing.B) {
    for i := 0; i < b.N; i++ {
        // ...
    }
}

The b.N is the number of times the test is run, and the b.N is automatically adjusted by the go test tool.

    BenchmarkSplit-8        10000000               215 ns/op

• The -8 means the test is run on the 8 GOMAXPROCS
• The 10000000 means the test is run 10000000 times.
• The 215 ns/op means the test takes 215 nanoseconds average per operation.

go test -bench=Xxx -benchmem can check the memory allocation and the number of allocations per operation.

    BenchmarkSplit-8        10000000               215 ns/op             112 B/op          3 allocs/op

• The 112 B/op means the test allocates 112 bytes per operation.
• The 3 allocs/op means the test allocates 3 times per operation.

Performance comparison #

// note: the n is the parameter of Fib not the b.N, the b.N is the number of times the test is run. it will be automatically adjusted by the go test tool.
func benchmarkFib(b *testing.B, n int) {
    for i := 0; i < b.N; i++ {
        Fib(n)
    }
}

func BenchmarkFib1(b *testing.B)  { benchmarkFib(b, 1) }
func BenchmarkFib2(b *testing.B)  { benchmarkFib(b, 2) }
func BenchmarkFib3(b *testing.B)  { benchmarkFib(b, 3) }

go test -bench=. will execute the benchmark test for all functions with the prefix Benchmark.

func BenchmarkSplit(b *testing.B) {
    time.Sleep(5 * time.Second) // some time-consuming operations
    b.ResetTimer()              // reset the timer(ignore the time above)
    for i := 0; i < b.N; i++ {
        // some time-consuming operations
    }
}

// you can also use this method

func BenchmarkSplit(b *testing.B) {
    b.StopTimer()
    // some time-consuming operations
    b.StartTimer()
    for i := 0; i < b.N; i++ {
        // some time-consuming operations
    }
}

Parallel test #

Signature:

func BenchmarkSplitParallel(b *testing.B) {
    // b.SetParallelism(1) // set the number of CPU to use
    b.RunParallel(func(pb *testing.PB) {
        for pb.Next() {
            // some time-consuming operations
        }
    })
}

Example test #

Signature:

func ExampleName() {
    // No parameters and no return
}