Table driven tests for generics

min-max.go

package number

import "golang.org/x/exp/constraints"

func Min[T constraints.Ordered](x, y T) T {
	if x <= y {
		return x
	}

	return y
}

func Max[t constraints.Ordered](x, y t) t {
	if y == Min(x, y) {
		return x
	}

	return y
}

min-max_test.go

package number_test

import (
	"testing"

	"generics/internal/number"

	"golang.org/x/exp/constraints"
)

type casesMinMax[T constraints.Ordered] []*struct {
	x, y, exp T
}

func testMin[T constraints.Ordered](cases casesMinMax[T]) func(*testing.T) {
	return func(t *testing.T) {
		t.Helper()

		if len(cases) == 0 {
			t.Fatal("no cases")
		}

		for _, c := range cases {
			if act := number.Min(c.x, c.y); act != c.exp {
				t.Fatalf("number.Min(%v, %v) != %v: %v", c.x, c.y, c.exp, act)
			}
		}
	}
}

func testMax[T constraints.Ordered](cases casesMinMax[T]) func(*testing.T) {
	return func(t *testing.T) {
		t.Helper()

		if len(cases) == 0 {
			t.Fatal("no cases")
		}

		for _, c := range cases {
			if act := number.Max(c.x, c.y); act != c.exp {
				t.Fatalf("number.Max(%v, %v) != %v: %v", c.x, c.y, c.exp, act)
			}
		}
	}
}

func TestMin(t *testing.T) {
	t.Parallel()

	t.Run("Integer", testMin(casesMinMax[int]{
		{0, -1, -1},
		{-1, 0, -1},
		{0, 0, 0},
		{0, 1, 0},
		{1, 0, 0},
	}))

	t.Run("Float", testMin(casesMinMax[float32]{
		{0, -0.5, -0.5},
		{-0.5, 0, -0.5},
		{0, 0, 0},
		{0, 0.5, 0},
		{0.5, 0, 0},
	}))

	t.Run("String", testMin(casesMinMax[string]{
		{"", "", ""},
		{"aa", "bb", "aa"},
		{"bb", "aa", "aa"},
	}))
}

func TestMax(t *testing.T) {
	t.Parallel()

	t.Run("Integer", testMax(casesMinMax[int]{
		{0, -1, 0},
		{-1, 0, 0},
		{0, 0, 0},
		{0, 1, 1},
		{1, 0, 1},
	}))

	t.Run("Float", testMax(casesMinMax[float32]{
		{0, -0.5, 0},
		{-0.5, 0, 0},
		{0, 0, 0},
		{0, 0.5, 0.5},
		{0.5, 0, 0.5},
	}))

	t.Run("String", testMax(casesMinMax[string]{
		{"", "", ""},
		{"aa", "bb", "bb"},
		{"bb", "aa", "bb"},
	}))
}