feat: new in slice matcher

gomock/matchers.go

@@ -271,6 +271,37 @@ func (m inAnyOrderMatcher) String() string {
 	return fmt.Sprintf("has the same elements as %v", m.x)
 }
 
+type inMatcher struct {
+	x interface{}
+}
+
+func (m inMatcher) Matches(x interface{}) bool {
+	matchers := m.prepareValue(m.x)
+	for _, matcher := range matchers {
+		if matcher.Matches(x) {
+			return true
+		}
+	}
+	return false
+}
+
+func (m inMatcher) prepareValue(x interface{}) []Matcher {
+	xValue := reflect.ValueOf(x)
+	kind := xValue.Kind()
+	if kind != reflect.Slice && kind != reflect.Array {
+		return nil
+	}
+	matchers := make([]Matcher, 0, xValue.Len())
+	for i := 0; i < xValue.Len(); i++ {
+		matchers = append(matchers, Eq(xValue.Index(i).Interface()))
+	}
+	return matchers
+}
+
+func (m inMatcher) String() string {
+	return fmt.Sprintf("match one of %v", m.x)
+}
+
 // Constructors
 
 // All returns a composite Matcher that returns true if and only all of the
@@ -339,3 +370,14 @@ func AssignableToTypeOf(x interface{}) Matcher {
 func InAnyOrder(x interface{}) Matcher {
 	return inAnyOrderMatcher{x}
 }
+
+// In is a Matcher that returns true if the received value Eq one of the elements
+//
+// Example usage:
+//   m := In([]int{1,2})
+//   m.Matches(1) // returns true
+//   m.Matches(2) // returns true
+//   m.Matches(3) // returns false
+func In(x interface{}) Matcher {
+	return inMatcher{x}
+}

gomock/matchers_test.go

@@ -293,3 +293,44 @@ func TestInAnyOrder(t *testing.T) {
 		})
 	}
 }
+
+func TestInMatcher_Matches(t *testing.T) {
+	tests := []struct {
+		name      string
+		wanted    interface{}
+		given     interface{}
+		wantMatch bool
+	}{
+		{
+			"match successfully",
+			[]int{1, 2},
+			2,
+			true,
+		},
+		{
+			"given not found",
+			[]int{1, 2},
+			3,
+			false,
+		},
+		{
+			"type not match, wanted should be slice",
+			1,
+			1,
+			false,
+		},
+		{
+			"empty slice",
+			[]int{},
+			1,
+			false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := gomock.In(tt.wanted).Matches(tt.given); got != tt.wantMatch {
+				t.Errorf("got = %v, wantMatch %v", got, tt.wantMatch)
+			}
+		})
+	}
+}