Table-driven tests

Table-driven tests define a slice of test cases containing inputs and expected outputs, then iterate over them in a single test function to run multiple scenarios. This pattern reduces code duplication and makes it easy to add new cases.

func TestParseNumeric(t *testing.T) {
	vectors := []struct {
		in   string
		want int64
		ok   bool
	}{
		{"0000000\x00", 0, true},
		{"0123456789", 0, false},
	}

	for _, v := range vectors {
		got, ok := parseNumeric(v.in)
		if ok != v.ok || got != v.want {
			t.Errorf("parseNumeric(%q): got (%d, %v), want (%d, %v)", v.in, got, ok, v.want, v.ok)
		}
	}
}

Table-driven tests let you write one test function that runs many different scenarios by listing them in a table. Instead of writing a separate function for every case, you just add a new row to your list. It is like checking a grocery list against your cart: you have one process, but you verify many items at once.