fix: more unit test coverage

Author: saahilmahato

src/test/java/com/thealgorithms/maths/prime/EulerPseudoprimeTest.java

@@ -10,21 +10,73 @@ class EulerPseudoprimeTest {
 
     @Test
     void testPrimeNumbers() {
-        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(7), 10));
-        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(13), 10));
-        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(101), 10));
+        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(7), 5));
+        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(13), 5));
+        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(101), 5));
     }
 
     @Test
     void testCompositeNumbers() {
-        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(9), 10));
-        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(21), 10));
-        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(221), 10));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(9), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(21), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(221), 5));
     }
 
     @Test
     void testEvenNumbers() {
-        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(4), 10));
-        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(100), 10));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(4), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(100), 5));
+    }
+
+    @Test
+    void testEdgeCases() {
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(0), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(1), 5));
+        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(2), 5));
+        assertTrue(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(3), 5));
+    }
+
+    @Test
+    void testSingleTrialConsistency() {
+        BigInteger n = BigInteger.valueOf(97);
+        boolean result1 = EulerPseudoprime.isProbablePrime(n, 1);
+        boolean result2 = EulerPseudoprime.isProbablePrime(n, 1);
+        assertEquals(result1, result2, "Results should be deterministic with constant seed");
+    }
+
+    @Test
+    void testJacobiSymbolBasicCases() throws Exception {
+        var method = EulerPseudoprime.class.getDeclaredMethod("jacobiSymbol", BigInteger.class, BigInteger.class);
+        method.setAccessible(true);
+
+        // (a/n) = (2/3) = -1
+        assertEquals(-1, (int) method.invoke(null, BigInteger.valueOf(2), BigInteger.valueOf(3)));
+
+        // (a/n) = (1/5) = 1
+        assertEquals(1, (int) method.invoke(null, BigInteger.ONE, BigInteger.valueOf(5)));
+
+        // (a/n) = (2/9) = 1
+        assertEquals(1, (int) method.invoke(null, BigInteger.valueOf(2), BigInteger.valueOf(9)));
+
+        // (a/n) = (3/9) = 0 since gcd(3,9)>1
+        assertEquals(0, (int) method.invoke(null, BigInteger.valueOf(3), BigInteger.valueOf(9)));
+    }
+
+    @Test
+    void testUniformRandomRange() throws Exception {
+        var method = EulerPseudoprime.class.getDeclaredMethod("uniformRandom", BigInteger.class, BigInteger.class);
+        method.setAccessible(true);
+
+        BigInteger min = BigInteger.TWO;
+        BigInteger max = BigInteger.valueOf(20);
+        BigInteger value = (BigInteger) method.invoke(null, min, max);
+
+        assertTrue(value.compareTo(min) >= 0 && value.compareTo(max) <= 0, "Random value should be within [min, max]");
+    }
+
+    @Test
+    void testCompositeWithZeroJacobiSymbol() {
+        // Choose n = 9, a = 3 → jacobi(3,9) = 0 should make it return false early
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(9), 1));
     }
 }