TUN-6868: Return left padded tracing ID when tracing identity is converted to string

tracing/identity.go

@@ -24,7 +24,7 @@ type Identity struct {
 
 // TODO: TUN-6604 Remove this. To reconstruct into Jaeger propagation format, convert tracingContext to tracing.Identity
 func (tc *Identity) String() string {
-	return fmt.Sprintf("%x%x:%x:0:%x", tc.traceIDUpper, tc.traceIDLower, tc.spanID, tc.flags)
+	return fmt.Sprintf("%016x%016x:%x:0:%x", tc.traceIDUpper, tc.traceIDLower, tc.spanID, tc.flags)
 }
 
 func (tc *Identity) MarshalBinary() ([]byte, error) {
@@ -68,14 +68,9 @@ func NewIdentity(trace string) (*Identity, error) {
 		return nil, fmt.Errorf("trace '%s' doesn't have exactly 4 parts separated by %s", trace, separator)
 	}
 	const base = 16
-	tracingID := parts[0]
-	if len(tracingID) == 0 {
-		return nil, fmt.Errorf("missing tracing ID")
-	}
-	if len(tracingID) != 32 {
-		// Correctly left pad the trace to a length of 32
-		left := traceID128bitsWidth - len(tracingID)
-		tracingID = strings.Repeat("0", left) + tracingID
+	tracingID, err := padTracingID(parts[0])
+	if err != nil {
+		return nil, err
 	}
 	traceIDUpper, err := strconv.ParseUint(tracingID[:16], base, 64)
 	if err != nil {
@@ -100,3 +95,16 @@ func NewIdentity(trace string) (*Identity, error) {
 		flags:        uint8(flags),
 	}, nil
 }
+
+func padTracingID(tracingID string) (string, error) {
+	if len(tracingID) == 0 {
+		return "", fmt.Errorf("missing tracing ID")
+	}
+	if len(tracingID) == traceID128bitsWidth {
+		return tracingID, nil
+	}
+	// Correctly left pad the trace to a length of 32
+	left := traceID128bitsWidth - len(tracingID)
+	paddedTracingID := strings.Repeat("0", left) + tracingID
+	return paddedTracingID, nil
+}

tracing/identity_test.go

@@ -10,40 +10,55 @@ func TestNewIdentity(t *testing.T) {
 	testCases := []struct {
 		testCase string
 		trace    string
-		valid    bool
+		expected string
 	}{
 		{
 			testCase: "full length trace",
 			trace:    "ec31ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
-			valid:    true,
+			expected: "ec31ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
 		},
 		{
 			testCase: "short trace ID",
 			trace:    "ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
-			valid:    true,
+			expected: "0000ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
+		},
+		{
+			testCase: "short trace ID with 0s in the middle",
+			trace:    "ad8a01fde11f000002efdce36873:52726f6cabc144f5:0:1",
+			expected: "0000ad8a01fde11f000002efdce36873:52726f6cabc144f5:0:1",
+		},
+		{
+			testCase: "short trace ID with 0s in the beginning and middle",
+			trace:    "001ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
+			expected: "0001ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0:1",
 		},
 		{
 			testCase: "no trace",
 			trace:    "",
-			valid:    false,
 		},
 		{
 			testCase: "missing flags",
 			trace:    "ec31ad8a01fde11fdcabe2efdce36873:52726f6cabc144f5:0",
-			valid:    false,
 		},
 		{
 			testCase: "missing separator",
 			trace:    "ec31ad8a01fde11fdcabe2efdce3687352726f6cabc144f501",
-			valid:    false,
 		},
 	}
 
 	for _, testCase := range testCases {
 		identity, err := NewIdentity(testCase.trace)
-		if testCase.valid {
-			require.NoError(t, err, testCase.testCase)
-			require.Equal(t, testCase.trace, identity.String())
+		if testCase.expected != "" {
+			require.NoError(t, err)
+			require.Equal(t, testCase.expected, identity.String())
+
+			serializedIdentity, err := identity.MarshalBinary()
+			require.NoError(t, err)
+			deserializedIdentity := new(Identity)
+			err = deserializedIdentity.UnmarshalBinary(serializedIdentity)
+			require.NoError(t, err)
+			require.Equal(t, identity, deserializedIdentity)
+
 		} else {
 			require.Error(t, err)
 			require.Nil(t, identity)