Merge pull request #335 from dominicbarnes/mock-arg-diff

Mock: Add diff to output when no exact match found

mock/mock.go

@@ -9,6 +9,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/davecgh/go-spew/spew"
+	"github.com/pmezard/go-difflib/difflib"
 	"github.com/stretchr/objx"
 	"github.com/stretchr/testify/assert"
 )
@@ -299,7 +301,7 @@ func (m *Mock) Called(arguments ...interface{}) Arguments {
 		closestFound, closestCall := m.findClosestCall(functionName, arguments...)
 
 		if closestFound {
-			panic(fmt.Sprintf("\n\nmock: Unexpected Method Call\n-----------------------------\n\n%s\n\nThe closest call I have is: \n\n%s\n", callString(functionName, arguments, true), callString(functionName, closestCall.Arguments, true)))
+			panic(fmt.Sprintf("\n\nmock: Unexpected Method Call\n-----------------------------\n\n%s\n\nThe closest call I have is: \n\n%s\n\n%s\n", callString(functionName, arguments, true), callString(functionName, closestCall.Arguments, true), diffArguments(arguments, closestCall.Arguments)))
 		} else {
 			panic(fmt.Sprintf("\nassert: mock: I don't know what to return because the method call was unexpected.\n\tEither do Mock.On(\"%s\").Return(...) first, or remove the %s() call.\n\tThis method was unexpected:\n\t\t%s\n\tat: %s", functionName, functionName, callString(functionName, arguments, true), assert.CallerInfo()))
 		}
@@ -700,3 +702,59 @@ func (args Arguments) Bool(index int) bool {
 	}
 	return s
 }
+
+func typeAndKind(v interface{}) (reflect.Type, reflect.Kind) {
+	t := reflect.TypeOf(v)
+	k := t.Kind()
+
+	if k == reflect.Ptr {
+		t = t.Elem()
+		k = t.Kind()
+	}
+	return t, k
+}
+
+func diffArguments(expected Arguments, actual Arguments) string {
+	for x := range expected {
+		if diffString := diff(expected[x], actual[x]); diffString != "" {
+			return fmt.Sprintf("Difference found in argument %v:\n\n%s", x, diffString)
+		}
+	}
+
+	return ""
+}
+
+// diff returns a diff of both values as long as both are of the same type and
+// are a struct, map, slice or array. Otherwise it returns an empty string.
+func diff(expected interface{}, actual interface{}) string {
+	if expected == nil || actual == nil {
+		return ""
+	}
+
+	et, ek := typeAndKind(expected)
+	at, _ := typeAndKind(actual)
+
+	if et != at {
+		return ""
+	}
+
+	if ek != reflect.Struct && ek != reflect.Map && ek != reflect.Slice && ek != reflect.Array {
+		return ""
+	}
+
+	spew.Config.SortKeys = true
+	e := spew.Sdump(expected)
+	a := spew.Sdump(actual)
+
+	diff, _ := difflib.GetUnifiedDiffString(difflib.UnifiedDiff{
+		A:        difflib.SplitLines(e),
+		B:        difflib.SplitLines(a),
+		FromFile: "Expected",
+		FromDate: "",
+		ToFile:   "Actual",
+		ToDate:   "",
+		Context:  1,
+	})
+
+	return diff
+}