FEAT: Support negative indexes in Array

array.go

@@ -168,6 +168,9 @@ func (a *Array) Value(index int) *Value {
 		return newValue(opChain, nil)
 	}
 
+	if index < 0 {
+		index = len(a.value) + index
+	}
 	if index < 0 || index >= len(a.value) {
 		opChain.fail(AssertionFailure{
 			Type:   AssertInRange,
@@ -208,6 +211,9 @@ func (a *Array) HasValue(index int, value interface{}) *Array {
 		return a
 	}
 
+	if index < 0 {
+		index = len(a.value) + index
+	}
 	if index < 0 || index >= len(a.value) {
 		opChain.fail(AssertionFailure{
 			Type:   AssertInRange,
@@ -262,6 +268,9 @@ func (a *Array) NotHasValue(index int, value interface{}) *Array {
 		return a
 	}
 
+	if index < 0 {
+		index = len(a.value) + index
+	}
 	if index < 0 || index >= len(a.value) {
 		opChain.fail(AssertionFailure{
 			Type:   AssertInRange,

array_test.go

@@ -351,7 +351,21 @@ func TestArray_Getters(t *testing.T) {
 		innerValue.chain.assert(t, success)
 	})
 
-	t.Run("value out of range", func(t *testing.T) {
+	t.Run("value negative", func(t *testing.T) {
+		reporter := newMockReporter(t)
+
+		data := []interface{}{"foo", 123.0}
+
+		value := NewArray(reporter, data)
+
+		innerValue := value.Value(-1)
+		assert.Equal(t, 123.0, innerValue.Raw())
+
+		value.chain.assert(t, success)
+		innerValue.chain.assert(t, success)
+	})
+
+	t.Run("value out of range (positive)", func(t *testing.T) {
 		reporter := newMockReporter(t)
 
 		data := []interface{}{"foo", 123.0}
@@ -364,6 +378,20 @@ func TestArray_Getters(t *testing.T) {
 		value.chain.assert(t, failure)
 		innerValue.chain.assert(t, failure)
 	})
+
+	t.Run("value out of range (negative)", func(t *testing.T) {
+		reporter := newMockReporter(t)
+
+		data := []interface{}{"foo", 123.0}
+
+		value := NewArray(reporter, data)
+
+		innerValue := value.Value(-3)
+		assert.NotNil(t, innerValue)
+
+		value.chain.assert(t, failure)
+		innerValue.chain.assert(t, failure)
+	})
 }
 
 func TestArray_IsEmpty(t *testing.T) {
@@ -1426,6 +1454,20 @@ func TestArray_HasValue(t *testing.T) {
 				wantHasValue:    success,
 				wantNotHasValue: failure,
 			},
+			{
+				name: "negative index check",
+				array: []interface{}{
+					123,
+					[]interface{}{"456", 789},
+					map[string]interface{}{
+						"a": "b",
+					},
+				},
+				index:           -3,
+				value:           123,
+				wantHasValue:    success,
+				wantNotHasValue: failure,
+			},
 			{
 				name: "out of bounds check",
 				array: []interface{}{