Go test parameterized

Question

In Python I can easily do

@pytest.mark.parametrize('input, expected', [(1, 2), [2, 3]])
def test_tutu(input, expected):
    assert input + 1 == expected

How can I do the same in Go, without writing myself a loop like this:

func tutu(a int) int {
    return a + 1
}

func Test_tutu(t *testing.T) {
    tests := []struct {
        input    int
        expected int
    }{
        {input: 1, expected: 2},
        {input: 2, expected: 3},
    }

    for _, tt := range tests {
        t.Run("", func(t *testing.T) {
            assert.Equal(t, tutu(tt.input), tt.expected)
        })
    }
}

So what would be the equivalent of this Python parametrize in Go?

def parametrize(all_args_name: str, all_values: List[Any], fn: Callable):
    args_name = all_args_name.split(',')
    for values in all_values:
        args = {k: v for k, v in zip(args_name, values)}
        fn(**args)

Gilo · Accepted Answer · 2022-07-04 22:46:12Z

2

The closest thing GO has is subtests, but you would still need to write the for loop, like you already did in the second example.

edited Jul 4, 2022 at 22:46

answered Jul 4, 2022 at 22:40

Gilo

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Comments

raphaelauv · Accepted Answer · 2022-07-05 06:21:12Z

2

I found a way using reflect

func parametrize[V any, T any](fn T, allValues [][]V) {
    v := reflect.ValueOf(fn)
    for _, a := range allValues {
        vargs := make([]reflect.Value, len(a))

        for i, b := range a {
            vargs[i] = reflect.ValueOf(b)
        }
        v.Call(vargs)
    }
}

func tutu(a int) int {
    return a + 1
}

func Test_tutu(t *testing.T) {
    testsArgs := [][]any{
        {t, 1, 2}, {t, 3, 4},
    }
    test := func(t *testing.T, input int, expected int) {
        assert.Equal(t, tutu(input), expected)
    }
    parametrize(test, testsArgs)
}

edited Jul 5, 2022 at 6:21

answered Jul 5, 2022 at 6:09

raphaelauv

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1 Comment

Zach Young Over a year ago

What do you like about your parameterize/reflection approach? I'm not new to Go, but I find that very difficult to read and understand. The explicit for-loop in your question is very readable.

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