support comparing byte slice

Signed-off-by: Ryan Leung <rleungx@gmail.com>

assert/assertion_compare.go

@@ -1,6 +1,7 @@
 package assert
 
 import (
+	"bytes"
 	"fmt"
 	"reflect"
 	"time"
@@ -32,7 +33,8 @@ var (
 
 	stringType = reflect.TypeOf("")
 
-	timeType = reflect.TypeOf(time.Time{})
+	timeType  = reflect.TypeOf(time.Time{})
+	bytesType = reflect.TypeOf([]byte{})
 )
 
 func compare(obj1, obj2 interface{}, kind reflect.Kind) (CompareType, bool) {
@@ -323,6 +325,26 @@ func compare(obj1, obj2 interface{}, kind reflect.Kind) (CompareType, bool) {
 
 			return compare(timeObj1.UnixNano(), timeObj2.UnixNano(), reflect.Int64)
 		}
+	case reflect.Slice:
+		{
+			// We only care about the []byte type.
+			if !canConvert(obj1Value, bytesType) {
+				break
+			}
+
+			// []byte can be compared!
+			byteObj1 := obj1Value.Bytes()
+			byteObj2 := obj2Value.Bytes()
+			if bytes.Compare(byteObj1, byteObj2) > 0 {
+				return compareGreater, true
+			}
+			if bytes.Equal(byteObj1, byteObj2) {
+				return compareEqual, true
+			}
+			if bytes.Compare(byteObj1, byteObj2) < 0 {
+				return compareLess, true
+			}
+		}
 	}
 
 	return compareEqual, false

assert/assertion_compare_test.go

@@ -22,6 +22,7 @@ func TestCompare(t *testing.T) {
 	type customFloat32 float32
 	type customFloat64 float64
 	type customString string
+	type customBytes []byte
 	for _, currCase := range []struct {
 		less    interface{}
 		greater interface{}
@@ -52,6 +53,8 @@ func TestCompare(t *testing.T) {
 		{less: customFloat32(1.23), greater: customFloat32(2.23), cType: "float32"},
 		{less: float64(1.23), greater: float64(2.34), cType: "float64"},
 		{less: customFloat64(1.23), greater: customFloat64(2.34), cType: "float64"},
+		{less: []byte{1, 1}, greater: []byte{1, 2}, cType: "[]byte"},
+		{less: customBytes([]byte{1, 1}), greater: customBytes([]byte{1, 2}), cType: "[]byte"},
 	} {
 		resLess, isComparable := compare(currCase.less, currCase.greater, reflect.ValueOf(currCase.less).Kind())
 		if !isComparable {
@@ -148,6 +151,7 @@ func TestGreater(t *testing.T) {
 		{less: uint64(1), greater: uint64(2), msg: `"1" is not greater than "2"`},
 		{less: float32(1.23), greater: float32(2.34), msg: `"1.23" is not greater than "2.34"`},
 		{less: float64(1.23), greater: float64(2.34), msg: `"1.23" is not greater than "2.34"`},
+		{less: []byte{1, 1}, greater: []byte{1, 2}, msg: `"[1 1]" is not greater than "[1 2]"`},
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Greater(out, currCase.less, currCase.greater))
@@ -189,6 +193,7 @@ func TestGreaterOrEqual(t *testing.T) {
 		{less: uint64(1), greater: uint64(2), msg: `"1" is not greater than or equal to "2"`},
 		{less: float32(1.23), greater: float32(2.34), msg: `"1.23" is not greater than or equal to "2.34"`},
 		{less: float64(1.23), greater: float64(2.34), msg: `"1.23" is not greater than or equal to "2.34"`},
+		{less: []byte{1, 1}, greater: []byte{1, 2}, msg: `"[1 1]" is not greater than or equal to "[1 2]"`},
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, GreaterOrEqual(out, currCase.less, currCase.greater))
@@ -230,6 +235,7 @@ func TestLess(t *testing.T) {
 		{less: uint64(1), greater: uint64(2), msg: `"2" is not less than "1"`},
 		{less: float32(1.23), greater: float32(2.34), msg: `"2.34" is not less than "1.23"`},
 		{less: float64(1.23), greater: float64(2.34), msg: `"2.34" is not less than "1.23"`},
+		{less: []byte{1, 1}, greater: []byte{1, 2}, msg: `"[1 2]" is not less than "[1 1]"`},
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, Less(out, currCase.greater, currCase.less))
@@ -271,6 +277,7 @@ func TestLessOrEqual(t *testing.T) {
 		{less: uint64(1), greater: uint64(2), msg: `"2" is not less than or equal to "1"`},
 		{less: float32(1.23), greater: float32(2.34), msg: `"2.34" is not less than or equal to "1.23"`},
 		{less: float64(1.23), greater: float64(2.34), msg: `"2.34" is not less than or equal to "1.23"`},
+		{less: []byte{1, 1}, greater: []byte{1, 2}, msg: `"[1 2]" is not less than or equal to "[1 1]"`},
 	} {
 		out := &outputT{buf: bytes.NewBuffer(nil)}
 		False(t, LessOrEqual(out, currCase.greater, currCase.less))