go test

example/
   |--calc.go
   |--calc_test.go

package main

func Add(a int, b int) (int) {
    return a + b
}

func minus(a int, b int) (int) {
    return a - b
}

func mul(a int, b int) (int) {
    return a * b
}

func div(a int, b int) (int) {
    return a / b
}

package main

import "testing"

func TestAdd_1(t *testing.T) {
	if ans := Add(1, 2); ans != 3 {
		t.Errorf("1 + 2 expected be 3, but %d got", ans)
	}
}

func TestAdd_2(t *testing.T) {
	if ans := Add(-10, -20); ans != -30 {
		t.Errorf("-10 + -20 expected be -30, but %d got", ans)
	}
}

func TestAdd_3(t *testing.T) {
	if ans := Add(-10, 10); ans != -0 {
		t.Errorf("-10 + 10 expected be -0, but %d got", ans)
	}
}

func Test_mul_1(t *testing.T) {
     if ans := mul(1, 10) ; ans != 10 {
         t.Errorf("1 * 10 expected be 10, but %d got", ans)
     }

     if ans := mul(1, -10) ; ans != -10 {
         t.Errorf("1 * -10 expected be -10, but %d got", ans)
     }

     if ans := mul(0, -10) ; ans != -0 {
         t.Errorf("0 * -10 expected be -0, but %d got", ans)
     }
}

example$ go test   -v
=== RUN   TestAdd_1
--- PASS: TestAdd_1 (0.00s)
=== RUN   TestAdd_2
--- PASS: TestAdd_2 (0.00s)
=== RUN   TestAdd_3
--- PASS: TestAdd_3 (0.00s)
=== RUN   Test_mul_1
--- PASS: Test_mul_1 (0.00s)
PASS
ok  	_/...../example	0.001s

$ go test -run TestAdd_3 -v
$go test

func TestMul(t *testing.T) {
	t.Run("pos", func(t *testing.T) {
		if mul(2, 3) != 6 {
			t.Fatal("fail")
		}

	})
	t.Run("neg", func(t *testing.T) {
		if mul(2, -3) != -6 {
			t.Fatal("fail")
		}
	})
}

// 推荐如下的写法
func TestMulComm(t *testing.T) {
	cases := []struct {
		Name  string
		A, B, Expected int
	}{
		{"pos", 2, 3, 6},
		{"neg", 2, -3, -6},
		{"zero", 2, 0, 0},
	}

	for _, c := range cases {
		t.Run(c.Name, func(t *testing.T) {
			if ans := mul(c.A, c.B); ans != c.Expected {
				t.Fatalf("%d * %d expected %d, but %d got",
					c.A, c.B, c.Expected, ans)
			}
		})
	}
}

go test -v db_tenant_test.go db_test.go  db_tenant.go logger.go
go test -v db_tenant_test.go db_test.go  db_tenant.go logger.go -test.run TestSortPolicy

go test -v db_tenant_test.go db_test.go  db_tenant.go logger.go -cover
# html文件输出
go test -v db_tenant_test.go db_test.go  db_tenant.go logger.go -coverprofile cover.out 
go tool cover -html=cover.out -o cover.html