fix: gcustom.MakeMatcher accepts nil as actual value (#666)

Author: houz42

gcustom/make_matcher.go

@@ -97,7 +97,9 @@ func MakeMatcher(matchFunc any, args ...any) CustomGomegaMatcher {
 		finalMatchFunc = reflect.MakeFunc(reflect.TypeOf(finalMatchFunc),
 			func(args []reflect.Value) []reflect.Value {
 				actual := args[0].Interface()
-				if reflect.TypeOf(actual).AssignableTo(t.In(0)) {
+				if actual == nil && reflect.TypeOf(actual) == reflect.TypeOf(nil) {
+					return matchFuncValue.Call([]reflect.Value{reflect.New(t.In(0)).Elem()})
+				} else if reflect.TypeOf(actual).AssignableTo(t.In(0)) {
 					return matchFuncValue.Call([]reflect.Value{reflect.ValueOf(actual)})
 				} else {
 					return []reflect.Value{

gcustom/make_matcher_test.go

@@ -148,6 +148,21 @@ var _ = Describe("MakeMatcher", func() {
 
 			})
 		})
+
+		Context("when the match func accepts a nil-able type", func() {
+			It("ensure nil matches the type", func() {
+				var passedIn any
+				m := gcustom.MakeMatcher(func(a *someType) (bool, error) {
+					passedIn = a
+					return true, nil
+				})
+
+				success, err := m.Match(nil)
+				Ω(success).Should(BeTrue())
+				Ω(err).ShouldNot(HaveOccurred())
+				Ω(passedIn).Should(BeNil())
+			})
+		})
 	})
 
 	It("calls the matchFunc and returns whatever it returns when Match is called", func() {