new unit test for modular sqrts with int arguments

Author: TilmanNeumann

src/main/java/de/tilman_neumann/jml/modular/ModularSqrtTest.java src/test/java/de/tilman_neumann/jml/modular/ModularSqrtPerformanceTest.java

@@ -19,12 +19,13 @@
 import org.apache.logging.log4j.LogManager;
 
 import de.tilman_neumann.jml.primes.probable.BPSWTest;
-import de.tilman_neumann.util.Ensure;
 import de.tilman_neumann.util.ConfigUtil;
 
-public class ModularSqrtTest {
-	private static final Logger LOG = LogManager.getLogger(ModularSqrtTest.class);
+public class ModularSqrtPerformanceTest {
+	private static final Logger LOG = LogManager.getLogger(ModularSqrtPerformanceTest.class);
 
+	private static final int NCOUNT = 100000;
+
 	private static final SecureRandom rng = new SecureRandom();
 	private static final BPSWTest bpsw = new BPSWTest();
 	private static final JacobiSymbol jacobiEngine = new JacobiSymbol();
@@ -65,26 +66,8 @@ private static int[] createNArray(int[] pList) {
 		}
 		return nArray;
 	}
-
-	private static void testCorrectness(int NCOUNT) {
-		ModularSqrt31 mse31 = new ModularSqrt31();
-	
-		LOG.info("Test correctness of " + NCOUNT + " p with p%8==5");
-		int[] pArray = createPArray(5, NCOUNT);
-		int[] nArray = createNArray(pArray);
-		for (int i=0; i<NCOUNT; i++) {
-			int a = nArray[i];
-			int p = pArray[i];
-			int tonelli = mse31.Tonelli_Shanks(a, p);
-			Ensure.ensureEquals((tonelli * (long)tonelli) % p, a%p);
-			
-			int case5Mod8 = mse31.case5Mod8(a, p);
-			Ensure.ensureEquals((case5Mod8 * (long)case5Mod8) % p, a%p);
-			Ensure.ensureEquals(tonelli, case5Mod8); // both returned the smaller sqrt
-		}
-	}
 
-	private static void testPerformance(int NCOUNT) {
+	private static void testPerformance() {
 		long t;
 		ModularSqrt31 mse31 = new ModularSqrt31();
 		LOG.info("Test performance with " + NCOUNT + " test numbers:");
@@ -150,7 +133,6 @@ private static void testPerformance(int NCOUNT) {
 	 */
 	public static void main(String[] args) {
 		ConfigUtil.initProject();
-		testCorrectness(100000);
-		testPerformance(100000);
+		testPerformance();
 	}
 }

src/test/java/de/tilman_neumann/jml/modular/ModularSqrtTest.java

@@ -0,0 +1,96 @@
+/*
+ * java-math-library is a Java library focused on number theory, but not necessarily limited to it. It is based on the PSIQS 4.0 factoring project.
+ * Copyright (C) 2018-2024 Tilman Neumann - [email protected]
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with this program;
+ * if not, see <http://www.gnu.org/licenses/>.
+ */
+package de.tilman_neumann.jml.modular;
+
+import static org.junit.Assert.assertEquals;
+
+import java.security.SecureRandom;
+
+import org.apache.logging.log4j.Logger;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.apache.logging.log4j.LogManager;
+
+import de.tilman_neumann.jml.primes.probable.BPSWTest;
+import de.tilman_neumann.util.ConfigUtil;
+
+public class ModularSqrtTest {
+	private static final Logger LOG = LogManager.getLogger(ModularSqrtTest.class);
+	
+	private static final int NCOUNT = 100000;
+	
+	private static final SecureRandom rng = new SecureRandom();
+	private static final BPSWTest bpsw = new BPSWTest();
+	private static final JacobiSymbol jacobiEngine = new JacobiSymbol();
+	private static final ModularSqrt31 mse31 = new ModularSqrt31();
+	
+	@BeforeClass
+	public static void setup() {
+		ConfigUtil.initProject();
+	}
+
+	@Test
+	public void testCase5Mod8() {
+		LOG.info("Test correctness of " + NCOUNT + " p with p%8==5");
+		int[] pArray = createPArray(5, NCOUNT);
+		int[] nArray = createNArray(pArray);
+		for (int i=0; i<NCOUNT; i++) {
+			int a = nArray[i];
+			int p = pArray[i];
+			int tonelli = mse31.Tonelli_Shanks(a, p);
+			assertEquals((tonelli * (long)tonelli) % p, a%p);
+			
+			int case5Mod8 = mse31.case5Mod8(a, p);
+			assertEquals((case5Mod8 * (long)case5Mod8) % p, a%p);
+			assertEquals(tonelli, case5Mod8); // both returned the smaller sqrt
+		}
+	}
+
+	private static int[] createPArray(int wantedPMod8, int count) {
+		int[] pArray = new int[count];
+		int i = 0;
+		while (i<count) {
+			// get non-negative random n
+			int n = rng.nextInt(Integer.MAX_VALUE);
+			// add n to the test set if it is an odd prime with the wanted modulus mod 8
+			if (n>2 && (n&7) == wantedPMod8 && bpsw.isProbablePrime(n)) {
+				pArray[i] = n;
+				i++;
+			}
+		}
+		return pArray;
+	}
+
+	/**
+	 * Create positive n having Jacobi(n|p) == 1 for all p in pArray.
+	 * @param pList
+	 * @return
+	 */
+	private static int[] createNArray(int[] pList) {
+		int count = pList.length;
+		int[] nArray = new int[count];
+		int i = 0;
+		while (i<count) {
+			// get non-negative random n
+			int n = rng.nextInt(Integer.MAX_VALUE);
+			// add n if it has Jacobi(n|p) = 1
+			int p = pList[i];
+			if (jacobiEngine.jacobiSymbol(n, p) == 1) {
+				nArray[i] = n;
+				i++;
+			}
+		}
+		return nArray;
+	}
+}