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dex/vendor/github.com/onsi/gomega/matchers/with_transform.go
2020-01-31 10:32:00 +01:00

73 lines
2.3 KiB
Go

package matchers
import (
"fmt"
"reflect"
"github.com/onsi/gomega/internal/oraclematcher"
"github.com/onsi/gomega/types"
)
type WithTransformMatcher struct {
// input
Transform interface{} // must be a function of one parameter that returns one value
Matcher types.GomegaMatcher
// cached value
transformArgType reflect.Type
// state
transformedValue interface{}
}
func NewWithTransformMatcher(transform interface{}, matcher types.GomegaMatcher) *WithTransformMatcher {
if transform == nil {
panic("transform function cannot be nil")
}
txType := reflect.TypeOf(transform)
if txType.NumIn() != 1 {
panic("transform function must have 1 argument")
}
if txType.NumOut() != 1 {
panic("transform function must have 1 return value")
}
return &WithTransformMatcher{
Transform: transform,
Matcher: matcher,
transformArgType: reflect.TypeOf(transform).In(0),
}
}
func (m *WithTransformMatcher) Match(actual interface{}) (bool, error) {
// return error if actual's type is incompatible with Transform function's argument type
actualType := reflect.TypeOf(actual)
if !actualType.AssignableTo(m.transformArgType) {
return false, fmt.Errorf("Transform function expects '%s' but we have '%s'", m.transformArgType, actualType)
}
// call the Transform function with `actual`
fn := reflect.ValueOf(m.Transform)
result := fn.Call([]reflect.Value{reflect.ValueOf(actual)})
m.transformedValue = result[0].Interface() // expect exactly one value
return m.Matcher.Match(m.transformedValue)
}
func (m *WithTransformMatcher) FailureMessage(_ interface{}) (message string) {
return m.Matcher.FailureMessage(m.transformedValue)
}
func (m *WithTransformMatcher) NegatedFailureMessage(_ interface{}) (message string) {
return m.Matcher.NegatedFailureMessage(m.transformedValue)
}
func (m *WithTransformMatcher) MatchMayChangeInTheFuture(_ interface{}) bool {
// TODO: Maybe this should always just return true? (Only an issue for non-deterministic transformers.)
//
// Querying the next matcher is fine if the transformer always will return the same value.
// But if the transformer is non-deterministic and returns a different value each time, then there
// is no point in querying the next matcher, since it can only comment on the last transformed value.
return oraclematcher.MatchMayChangeInTheFuture(m.Matcher, m.transformedValue)
}