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package gopter_test
import (
"fmt"
"reflect"
"sort"
"github.com/leanovate/gopter"
"github.com/leanovate/gopter/gen"
"github.com/leanovate/gopter/prop"
)
func wrong_biggest(ns []int) (int, error) {
if len(ns) == 0 {
return 0, fmt.Errorf("slice must have at least one element")
}
return ns[0], nil
}
func Example_biggest() {
parameters := gopter.DefaultTestParameters()
parameters.Rng.Seed(1234) // Just for this example to generate reproducible results
properties := gopter.NewProperties(parameters)
properties.Property("Non-zero length small int slice", prop.ForAll(
func(ns []int) bool {
result, _ := wrong_biggest(ns)
sort.Slice(ns, func(i, j int) bool {
return ns[i] > ns[j]
})
return result == ns[0]
},
gen.SliceOf(gen.IntRange(0, 20),
reflect.TypeOf(int(0))).
SuchThat(func(v interface{}) bool {
return len(v.([]int)) > 0
}),
))
// When using testing.T you might just use: properties.TestingRun(t)
properties.Run(gopter.ConsoleReporter(false))
// Output:
// ! Non-zero length small int slice: Falsified after 1 passed tests.
// ARG_0: [0 5 0]
// ARG_0_ORIGINAL (1 shrinks): [0 7 5]
}
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