/
have_value.go
74 lines (66 loc) · 2.44 KB
/
have_value.go
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package matchers
import (
"errors"
"reflect"
"github.com/onsi/gomega/format"
"github.com/onsi/gomega/types"
)
const maxIndirections = 31
// HaveValue applies the given matcher to the value of actual, optionally and
// repeatedly dereferencing pointers or taking the concrete value of interfaces.
// Thus, the matcher will always be applied to non-pointer and non-interface
// values only. HaveValue will fail with an error if a pointer or interface is
// nil. It will also fail for more than 31 pointer or interface dereferences to
// guard against mistakenly applying it to arbitrarily deep linked pointers.
//
// HaveValue differs from gstruct.PointTo in that it does not expect actual to
// be a pointer (as gstruct.PointTo does) but instead also accepts non-pointer
// and even interface values.
//
// actual := 42
// Expect(actual).To(HaveValue(42))
// Expect(&actual).To(HaveValue(42))
func HaveValue(matcher types.GomegaMatcher) types.GomegaMatcher {
return &HaveValueMatcher{
Matcher: matcher,
}
}
type HaveValueMatcher struct {
Matcher types.GomegaMatcher // the matcher to apply to the "resolved" actual value.
resolvedActual interface{} // the ("resolved") value.
}
func (m *HaveValueMatcher) Match(actual interface{}) (bool, error) {
val := reflect.ValueOf(actual)
for allowedIndirs := maxIndirections; allowedIndirs > 0; allowedIndirs-- {
// return an error if value isn't valid. Please note that we cannot
// check for nil here, as we might not deal with a pointer or interface
// at this point.
if !val.IsValid() {
return false, errors.New(format.Message(
actual, "not to be <nil>"))
}
switch val.Kind() {
case reflect.Ptr, reflect.Interface:
// resolve pointers and interfaces to their values, then rinse and
// repeat.
if val.IsNil() {
return false, errors.New(format.Message(
actual, "not to be <nil>"))
}
val = val.Elem()
continue
default:
// forward the final value to the specified matcher.
m.resolvedActual = val.Interface()
return m.Matcher.Match(m.resolvedActual)
}
}
// too many indirections: extreme star gazing, indeed...?
return false, errors.New(format.Message(actual, "too many indirections"))
}
func (m *HaveValueMatcher) FailureMessage(_ interface{}) (message string) {
return m.Matcher.FailureMessage(m.resolvedActual)
}
func (m *HaveValueMatcher) NegatedFailureMessage(_ interface{}) (message string) {
return m.Matcher.NegatedFailureMessage(m.resolvedActual)
}