feat: add euler primality test (#6680)

* feat: add euler primality test * refactor: use fixed seed * fix: more unit test coverage * fix: add mock tests for edge cases * fix: styling issues * refactor: remove duplicate tests * refactor: reduce static imports * refactor: remove unnecessary tests * refactor: move to maths package --------- Co-authored-by: a <alexanderklmn@gmail.com>
2026-03-13 08:40:43 +08:00 · 2025-10-07 00:08:32 +05:45
parent 8ca2d9f820
commit 9f985b2549
2 changed files with 201 additions and 0 deletions
--- a/src/test/java/com/thealgorithms/maths/EulerPseudoprimeTest.java
+++ b/src/test/java/com/thealgorithms/maths/EulerPseudoprimeTest.java
@@ -0,0 +1,93 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+
+import java.math.BigInteger;
+import org.junit.jupiter.api.Test;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
+
+class EulerPseudoprimeTest {
+
+    @Test
+    void testPrimeNumbers() {
+        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), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(21), 5));
+        assertFalse(EulerPseudoprime.isProbablePrime(BigInteger.valueOf(221), 5));
+    }
+
+    @Test
+    void testEvenNumbers() {
+        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 testIsProbablePrimeWhenJacobiSymbolIsZero() {
+        try (MockedStatic<EulerPseudoprime> mockedPrimality = Mockito.mockStatic(EulerPseudoprime.class, Mockito.CALLS_REAL_METHODS)) {
+
+            // Mock jacobiSymbol to return 0 to test the branch
+            mockedPrimality.when(() -> EulerPseudoprime.jacobiSymbol(any(BigInteger.class), any(BigInteger.class))).thenReturn(0);
+
+            boolean result = EulerPseudoprime.isProbablePrime(BigInteger.valueOf(15), 1);
+
+            assertFalse(result);
+        }
+    }
+
+    @Test
+    void testJacobiSymbolThrowsForEvenOrNonPositiveN() throws Exception {
+        var method = EulerPseudoprime.class.getDeclaredMethod("jacobiSymbol", BigInteger.class, BigInteger.class);
+
+        // Helper lambda to unwrap InvocationTargetException
+        Runnable invokeJacobi = () -> {
+            try {
+                method.invoke(null, BigInteger.valueOf(2), BigInteger.valueOf(8));
+            } catch (Exception e) {
+                // unwrap
+                Throwable cause = e.getCause();
+                if (cause instanceof IllegalArgumentException) {
+                    throw (IllegalArgumentException) cause;
+                } else {
+                    throw new RuntimeException(e);
+                }
+            }
+        };
+
+        // Now check that it actually throws
+        assertThrows(IllegalArgumentException.class, invokeJacobi::run);
+
+        // Another case: non-positive n
+        Runnable invokeJacobi2 = () -> {
+            try {
+                method.invoke(null, BigInteger.valueOf(5), BigInteger.valueOf(-3));
+            } catch (Exception e) {
+                Throwable cause = e.getCause();
+                if (cause instanceof IllegalArgumentException) {
+                    throw (IllegalArgumentException) cause;
+                } else {
+                    throw new RuntimeException(e);
+                }
+            }
+        };
+        assertThrows(IllegalArgumentException.class, invokeJacobi2::run);
+    }
+}