Extract method to evaluate closest match

mock/mock.go

@@ -297,27 +297,52 @@ func (m *Mock) findExpectedCall(method string, arguments ...interface{}) (int, *
 	return -1, expectedCall
 }
 
+type matchCandidate struct {
+	call      *Call
+	mismatch  string
+	diffCount int
+}
+
+func (c matchCandidate) isBetterMatchThan(other matchCandidate) bool {
+	if c.call == nil {
+		return false
+	}
+	if other.call == nil {
+		return true
+	}
+
+	if c.diffCount > other.diffCount {
+		return false
+	}
+	if c.diffCount < other.diffCount {
+		return true
+	}
+
+	if c.call.Repeatability > other.call.Repeatability {
+		return true
+	}
+	return false
+}
+
 func (m *Mock) findClosestCall(method string, arguments ...interface{}) (*Call, string) {
-	var diffCount int
-	var repeatability int
-	var closestCall *Call
-	var err string
+	var bestMatch matchCandidate
 
 	for _, call := range m.expectedCalls() {
 		if call.Method == method {
 
 			errInfo, tempDiffCount := call.Arguments.Diff(arguments)
-			if tempDiffCount < diffCount || diffCount == 0 || (tempDiffCount == diffCount && call.Repeatability > repeatability) {
-				diffCount = tempDiffCount
-				repeatability = call.Repeatability
-				closestCall = call
-				err = errInfo
+			tempCandidate := matchCandidate{
+				call:      call,
+				mismatch:  errInfo,
+				diffCount: tempDiffCount,
+			}
+			if tempCandidate.isBetterMatchThan(bestMatch) {
+				bestMatch = tempCandidate
 			}
-
 		}
 	}
 
-	return closestCall, err
+	return bestMatch.call, bestMatch.mismatch
 }
 
 func callString(method string, arguments Arguments, includeArgumentValues bool) string {