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* Add HaveValue matcher * improves HaveValue matcher documentation and tests * use resolved value in failure msgs, make nils and too many indirections errors instead of failures * fix inverted failure message; add corresponding tests
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package matchers | ||
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import ( | ||
"errors" | ||
"reflect" | ||
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"github.com/onsi/gomega/format" | ||
"github.com/onsi/gomega/types" | ||
) | ||
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const maxIndirections = 31 | ||
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// 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, | ||
} | ||
} | ||
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type HaveValueMatcher struct { | ||
Matcher types.GomegaMatcher // the matcher to apply to the "resolved" actual value. | ||
resolvedActual interface{} // the ("resolved") value. | ||
} | ||
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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")) | ||
} | ||
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func (m *HaveValueMatcher) FailureMessage(_ interface{}) (message string) { | ||
return m.Matcher.FailureMessage(m.resolvedActual) | ||
} | ||
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func (m *HaveValueMatcher) NegatedFailureMessage(_ interface{}) (message string) { | ||
return m.Matcher.NegatedFailureMessage(m.resolvedActual) | ||
} |
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package matchers_test | ||
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import ( | ||
"reflect" | ||
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. "github.com/onsi/ginkgo/v2" | ||
. "github.com/onsi/gomega" | ||
. "github.com/onsi/gomega/matchers" | ||
) | ||
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type I interface { | ||
M() | ||
} | ||
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type S struct { | ||
V int | ||
} | ||
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func (s S) M() {} | ||
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var _ = Describe("HaveValue", func() { | ||
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It("should fail when passed nil", func() { | ||
var p *struct{} | ||
m := HaveValue(BeNil()) | ||
Expect(m.Match(p)).Error().To(MatchError(MatchRegexp("not to be <nil>$"))) | ||
}) | ||
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It("should fail when passed nil indirectly", func() { | ||
var p *struct{} | ||
m := HaveValue(BeNil()) | ||
Expect(m.Match(&p)).Error().To(MatchError(MatchRegexp("not to be <nil>$"))) | ||
}) | ||
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It("should use the matcher's failure message", func() { | ||
m := HaveValue(Equal(42)) | ||
Expect(m.Match(666)).To(BeFalse()) | ||
Expect(m.FailureMessage(nil)).To(Equal("Expected\n <int>: 666\nto equal\n <int>: 42")) | ||
Expect(m.NegatedFailureMessage(nil)).To(Equal("Expected\n <int>: 666\nnot to equal\n <int>: 42")) | ||
}) | ||
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It("should unwrap the value pointed to, even repeatedly", func() { | ||
i := 1 | ||
Expect(&i).To(HaveValue(Equal(1))) | ||
Expect(&i).NotTo(HaveValue(Equal(2))) | ||
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pi := &i | ||
Expect(pi).To(HaveValue(Equal(1))) | ||
Expect(pi).NotTo(HaveValue(Equal(2))) | ||
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Expect(&pi).To(HaveValue(Equal(1))) | ||
Expect(&pi).NotTo(HaveValue(Equal(2))) | ||
}) | ||
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It("shouldn't endlessly star-gaze", func() { | ||
dave := "It's full of stars!" | ||
stargazer := reflect.ValueOf(dave) | ||
for stars := 1; stars <= 31; stars++ { | ||
p := reflect.New(stargazer.Type()) | ||
p.Elem().Set(stargazer) | ||
stargazer = p | ||
} | ||
m := HaveValue(Equal(dave)) | ||
Expect(m.Match(stargazer.Interface())).Error().To( | ||
MatchError(MatchRegexp(`too many indirections`))) | ||
Expect(m.Match(stargazer.Elem().Interface())).To(BeTrue()) | ||
}) | ||
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It("should unwrap the value of an interface", func() { | ||
var i I = &S{V: 42} | ||
Expect(i).To(HaveValue(Equal(S{V: 42}))) | ||
Expect(i).NotTo(HaveValue(Equal(S{}))) | ||
}) | ||
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}) |