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package gopter_test
import (
"reflect"
"github.com/leanovate/gopter"
"github.com/leanovate/gopter/gen"
"github.com/leanovate/gopter/prop"
)
func Example_flatmap() {
type IntPair struct {
Fst int
Snd int
}
// Generate a pair of integers, such that the first
// is in the range of 10-20 and the second in the
// in the range of 2k-50, depending on the value of
// the first.
genIntPair := func() gopter.Gen {
return gen.IntRange(10, 20).FlatMap(func(v interface{}) gopter.Gen {
k := v.(int)
return gen.IntRange(2*k, 50).Map(func(m int) IntPair {
return IntPair{Fst: k, Snd: m}
})
},
reflect.TypeOf(int(0)))
}
parameters := gopter.DefaultTestParameters()
parameters.Rng.Seed(1234) // Just for this example to generate reproducible results
properties := gopter.NewProperties(parameters)
properties.Property("Generate a dependent pair of integers", prop.ForAll(
func(p IntPair) bool {
a := p.Fst
b := p.Snd
return a*2 <= b
},
genIntPair(),
))
// When using testing.T you might just use: properties.TestingRun(t)
properties.Run(gopter.ConsoleReporter(false))
// Output:
// + Generate a dependent pair of integers: OK, passed 100 tests.
}
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