Fix jsonpath slice step handling

staging/src/k8s.io/client-go/util/jsonpath/jsonpath.go

@@ -273,12 +273,16 @@ func (j *JSONPath) evalArray(input []reflect.Value, node *ArrayNode) ([]reflect.
 			return result, nil
 		}
 
-		if !params[2].Known {
+		value = value.Slice(params[0].Value, params[1].Value)
-			value = value.Slice(params[0].Value, params[1].Value)
+
-		} else {
+		step := 1
-			value = value.Slice3(params[0].Value, params[1].Value, params[2].Value)
+		if params[2].Known {
+			if params[2].Value <= 0 {
+				return input, fmt.Errorf("step must be >= 0")
+			}
+			step = params[2].Value
 		}
-		for i := 0; i < value.Len(); i++ {
+		for i := 0; i < value.Len(); i += step {
 			result = append(result, value.Index(i))
 		}
 	}

staging/src/k8s.io/client-go/util/jsonpath/jsonpath_test.go

@@ -40,12 +40,15 @@ func testJSONPath(tests []jsonpathTest, allowMissingKeys bool, t *testing.T) {
 		j.AllowMissingKeys(allowMissingKeys)
 		err := j.Parse(test.template)
 		if err != nil {
-			t.Errorf("in %s, parse %s error %v", test.name, test.template, err)
+			if !test.expectError {
+				t.Errorf("in %s, parse %s error %v", test.name, test.template, err)
+			}
+			continue
 		}
 		buf := new(bytes.Buffer)
 		err = j.Execute(buf, test.input)
 		if test.expectError {
-			if test.expectError && err == nil {
+			if err == nil {
 				t.Errorf("in %s, expected execute error", test.name)
 			}
 			continue
@@ -519,3 +522,133 @@ func TestNegativeIndex(t *testing.T) {
 		t,
 	)
 }
+
+func TestStep(t *testing.T) {
+	var input = []byte(
+		`{
+			"apiVersion": "v1",
+			"kind": "Pod",
+			"spec": {
+				"containers": [
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake0"
+					},
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake1"
+					},
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake2"
+					},
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake3"
+					},
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake4"
+					},
+					{
+						"image": "radial/busyboxplus:curl",
+						"name": "fake5"
+					}]}}`)
+
+	var data interface{}
+	err := json.Unmarshal(input, &data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testJSONPath(
+		[]jsonpathTest{
+			{
+				"test containers[0:], it equals containers[0:6:1]",
+				`{.spec.containers[0:].name}`,
+				data,
+				"fake0 fake1 fake2 fake3 fake4 fake5",
+				false,
+			},
+			{
+				"test containers[0:6:], it equals containers[0:6:1]",
+				`{.spec.containers[0:6:].name}`,
+				data,
+				"fake0 fake1 fake2 fake3 fake4 fake5",
+				false,
+			},
+			{
+				"test containers[0:6:1]",
+				`{.spec.containers[0:6:1].name}`,
+				data,
+				"fake0 fake1 fake2 fake3 fake4 fake5",
+				false,
+			},
+			{
+				"test containers[0:6:0], it errors",
+				`{.spec.containers[0:6:0].name}`,
+				data,
+				"",
+				true,
+			},
+			{
+				"test containers[0:6:-1], it errors",
+				`{.spec.containers[0:6:-1].name}`,
+				data,
+				"",
+				true,
+			},
+			{
+				"test containers[1:4:2]",
+				`{.spec.containers[1:4:2].name}`,
+				data,
+				"fake1 fake3",
+				false,
+			},
+			{
+				"test containers[1:4:3]",
+				`{.spec.containers[1:4:3].name}`,
+				data,
+				"fake1",
+				false,
+			},
+			{
+				"test containers[1:4:4]",
+				`{.spec.containers[1:4:4].name}`,
+				data,
+				"fake1",
+				false,
+			},
+			{
+				"test containers[0:6:2]",
+				`{.spec.containers[0:6:2].name}`,
+				data,
+				"fake0 fake2 fake4",
+				false,
+			},
+			{
+				"test containers[0:6:3]",
+				`{.spec.containers[0:6:3].name}`,
+				data,
+				"fake0 fake3",
+				false,
+			},
+			{
+				"test containers[0:6:5]",
+				`{.spec.containers[0:6:5].name}`,
+				data,
+				"fake0 fake5",
+				false,
+			},
+			{
+				"test containers[0:6:6]",
+				`{.spec.containers[0:6:6].name}`,
+				data,
+				"fake0",
+				false,
+			},
+		},
+		false,
+		t,
+	)
+}

staging/src/k8s.io/client-go/util/jsonpath/parser.go

@@ -46,7 +46,7 @@ type Parser struct {
 var (
 	ErrSyntax        = errors.New("invalid syntax")
 	dictKeyRex       = regexp.MustCompile(`^'([^']*)'$`)
-	sliceOperatorRex = regexp.MustCompile(`^(-?[\d]*)(:-?[\d]*)?(:[\d]*)?$`)
+	sliceOperatorRex = regexp.MustCompile(`^(-?[\d]*)(:-?[\d]*)?(:-?[\d]*)?$`)
 )
 
 // Parse parsed the given text and return a node Parser.

staging/src/k8s.io/client-go/util/jsonpath/parser_test.go

@@ -140,7 +140,6 @@ func TestFailParser(t *testing.T) {
 		{"unrecognized character", "{*}", "unrecognized character in action: U+002A '*'"},
 		{"invalid number", "{+12.3.0}", "cannot parse number +12.3.0"},
 		{"unterminated array", "{[1}", "unterminated array"},
-		{"invalid index", "{[::-1]}", "invalid array index ::-1"},
 		{"unterminated filter", "{[?(.price]}", "unterminated filter"},
 	}
 	for _, test := range failParserTests {