Increased test coverage for util/random

util/random/rand_test.go

@@ -3,6 +3,7 @@ package random
 import (
 	"bytes"
 	"crypto/rand"
+	"math/big"
 	"strings"
 	"testing"
 )
@@ -84,3 +85,59 @@ func TestIncorrectSize(t *testing.T) {
 	dst := make([]byte, size+1)
 	cipher.XORKeyStream(dst, src)
 }
+
+func TestBits(t *testing.T) {
+	testCases := []struct {
+		bitlen uint // input bit length
+		exact  bool // whether the exact bit length should be enforced
+	}{
+		{bitlen: 128, exact: false},
+		{bitlen: 256, exact: true},
+		{bitlen: 512, exact: false},
+		{bitlen: 1024, exact: true},
+	}
+
+	for _, tc := range testCases {
+		r := strings.NewReader("some io.Reader stream to be used for testing")
+		cipher := New(r, rand.Reader)
+
+		bigIntBytes := Bits(tc.bitlen, tc.exact, cipher)
+		bigInt := new(big.Int).SetBytes(bigIntBytes)
+
+		// Check if the bit length matches the expected length
+		expectedBitLen := tc.bitlen
+		if tc.exact && uint(bigInt.BitLen()) != expectedBitLen {
+			t.Errorf("Generated BigInt with exact bits doesn't match the expected bit length: got %d, expected %d", bigInt.BitLen(), expectedBitLen)
+		} else if !tc.exact && uint(bigInt.BitLen()) > expectedBitLen {
+			t.Errorf("Generated BigInt with more bits than maximum bit length: got %d, expected at most %d", bigInt.BitLen(), expectedBitLen)
+		}
+	}
+}
+
+func TestInt(t *testing.T) {
+	testCases := []struct {
+		modulusBitLen uint // Bit length of the modulus
+	}{
+		{128},
+		{256},
+		{512},
+		{1024},
+	}
+
+	for _, tc := range testCases {
+		modulus, err := rand.Prime(rand.Reader, int(tc.modulusBitLen))
+		if err != nil {
+			t.Fatalf("Failed to generate random prime: %v", err)
+		}
+
+		r := strings.NewReader("some io.Reader stream to be used for testing")
+		cipher := New(r, rand.Reader)
+
+		randomInt := Int(modulus, cipher)
+
+		// Check if the generated BigInt is less than the modulus
+		if randomInt.Cmp(modulus) >= 0 {
+			t.Errorf("Generated BigInt %v is not less than the modulus %v", randomInt, modulus)
+		}
+	}
+}