Bug-Fix: ABI encode infer to slice IsNil handler removal

data/abi/abi_encode.go

@@ -204,12 +204,8 @@ func inferToSlice(value interface{}) ([]interface{}, error) {
 	if reflectVal.Kind() != reflect.Slice && reflectVal.Kind() != reflect.Array {
 		return nil, fmt.Errorf("cannot infer an interface value as a slice of interface element")
 	}
-	if reflectVal.IsNil() {
-		if reflectVal.Kind() == reflect.Slice {
-			return nil, nil
-		}
-		return nil, fmt.Errorf("cannot infer nil value for array kind interface")
-	}
+	// * if input is a slice, with nil, then reflectVal.Len() == 0
+	// * if input is an array, it is not possible it is nil
 	values := make([]interface{}, reflectVal.Len())
 	for i := 0; i < reflectVal.Len(); i++ {
 		values[i] = reflectVal.Index(i).Interface()

data/abi/abi_encode_test.go

@@ -1224,3 +1224,44 @@ func TestParseMethodSignature(t *testing.T) {
 		})
 	}
 }
+
+func TestInferToSlice(t *testing.T) {
+	partitiontest.PartitionTest(t)
+
+	var emptySlice []int
+	tests := []struct {
+		toBeInferred interface{}
+		length       int
+	}{
+		{
+			toBeInferred: []int{},
+			length:       0,
+		},
+		{
+			toBeInferred: make([]int, 0),
+			length:       0,
+		},
+		{
+			toBeInferred: emptySlice,
+			length:       0,
+		},
+		{
+			toBeInferred: [0]int{},
+			length:       0,
+		},
+		{
+			toBeInferred: [32]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32},
+			length:       32,
+		},
+		{
+			toBeInferred: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32},
+			length:       32,
+		},
+	}
+
+	for i, test := range tests {
+		inferredSlice, err := inferToSlice(test.toBeInferred)
+		require.NoError(t, err, "inferToSlice on testcase %d failed to successfully infer %v", i, test.toBeInferred)
+		require.Equal(t, test.length, len(inferredSlice), "inferToSlice on testcase %d inferred different length, expected %d", i, test.length)
+	}
+}