fix: accept null values and buffers in the COMP-3 codec

CHANGELOG.md

@@ -14,6 +14,10 @@ Types of changes
 - `Fixed` for any bug fixes.
 - `Security` in case of vulnerabilities.
 
+## [0.3.1]
+
+- `Fixed` accept null values and buffers in the COMP-3 codec.
+
 ## [0.3.0]
 
 - `Added` COMP-3 codec now accepts both `.` and `,` as decimal separators from JSON input.

pkg/posimap/core/codec/comp3.go

@@ -78,6 +78,10 @@ func (c *Comp3) Decode(buffer api.Buffer, offset int) (any, error) {
 		return nil, fmt.Errorf("%w", err) // return error if buffer is too short
 	}
 
+	if isNull(bytes) {
+		return nil, nil //nolint:nilnil
+	}
+
 	for byteIndex, byteVal := range bytes {
 		if byteIndex*2 == c.intDigits {
 			result.WriteRune(c.sep)
@@ -111,6 +115,15 @@ func (c *Comp3) Decode(buffer api.Buffer, offset int) (any, error) {
 }
 
 func (c *Comp3) Encode(buffer api.Buffer, offset int, value any) error {
+	if value == nil {
+		// write null value (all bytes set to zero)
+		if err := buffer.Write(offset, make([]byte, c.size)); err != nil {
+			return fmt.Errorf("%w", err)
+		}
+
+		return nil
+	}
+
 	nibbleSign, str, err := c.detectSignAndAddLeadingZeroes(value)
 	if err != nil {
 		return err
@@ -266,3 +279,13 @@ func handleSign(byteVal byte) (string, error) {
 
 	return "", nil
 }
+
+func isNull(bytes []byte) bool {
+	for _, b := range bytes {
+		if b != 0 {
+			return false
+		}
+	}
+
+	return true
+}

pkg/posimap/core/codec/comp3_test.go

@@ -122,6 +122,14 @@ func TestComp3_Decode(t *testing.T) {
 			sep:       ',',
 			expected:  "+12345,67",
 		},
+		{
+			name:      "null buffer",
+			data:      []byte{0x00, 0x00, 0x00, 0x00},
+			intDigits: 5,
+			decDigits: 2,
+			sep:       ',',
+			expected:  nil,
+		},
 	}
 
 	for _, testcase := range tests {
@@ -285,6 +293,14 @@ func TestComp3_Encode(t *testing.T) {
 			sep:       '.', // even if the expected separator is '.', accept ',' in input
 			expected:  []byte{0x12, 0x34, 0x56, 0x7C},
 		},
+		{
+			name:      "null value",
+			value:     nil,
+			intDigits: 5,
+			decDigits: 2,
+			sep:       '.',
+			expected:  []byte{0x00, 0x00, 0x00, 0x00},
+		},
 	}
 
 	for _, testcase := range tests {