Changes to be committed:

modified:   pkg/obioptions/version.go
	modified:   pkg/obitools/obitagpcr/pcrtag.go
	modified:   pkg/obiutils/abs.go
	new file:   pkg/obiutils/abs_test.go

pkg/obiutils/abs.go

@@ -2,9 +2,13 @@ package obiutils
 
 import "golang.org/x/exp/constraints"
 
+// Abs returns the absolute value of x.
+//
+// It is a generic function that can be used on any signed type.
 func Abs[T constraints.Signed](x T) T {
 	if x < 0 {
 		return -x
 	}
+
 	return x
 }

pkg/obiutils/abs_test.go

@@ -0,0 +1,44 @@
+package obiutils_test
+
+import (
+	"testing"
+
+	"git.metabarcoding.org/obitools/obitools4/obitools4/pkg/obiutils"
+)
+
+func TestAbs(t *testing.T) {
+	// Test cases for positive integers
+	testCasesPositive := []struct {
+		input    int
+		expected int
+	}{
+		{0, 0},
+		{1, 1},
+		{5, 5},
+		{10, 10},
+	}
+
+	for _, tc := range testCasesPositive {
+		result := obiutils.Abs(tc.input)
+		if result != tc.expected {
+			t.Errorf("Abs(%d) = %d; want %d", tc.input, result, tc.expected)
+		}
+	}
+
+	// Test cases for negative integers
+	testCasesNegative := []struct {
+		input    int
+		expected int
+	}{
+		{-1, 1},
+		{-5, 5},
+		{-10, 10},
+	}
+
+	for _, tc := range testCasesNegative {
+		result := obiutils.Abs(tc.input)
+		if result != tc.expected {
+			t.Errorf("Abs(%d) = %d; want %d", tc.input, result, tc.expected)
+		}
+	}
+}