Tests for modular arithmetic

Author: SzymonStankiewicz

test/com/jwetherell/algorithms/mathematics/test/ModularArithmetic.java

@@ -0,0 +1,129 @@
+package com.jwetherell.algorithms.mathematics.test;
+
+import com.jwetherell.algorithms.mathematics.Modular;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class ModularArithmetic {
+
+    @Test
+    public void sumTest() {
+        assertEquals(4,
+                Modular.add(-3, 22, 5));
+
+        assertEquals(Long.MAX_VALUE-2,
+                Modular.add(Long.MAX_VALUE-1, Long.MAX_VALUE-1, Long.MAX_VALUE));
+
+        assertEquals(2,
+                Modular.add(1-Long.MAX_VALUE, 1-Long.MAX_VALUE, Long.MAX_VALUE));
+
+
+        assertEquals(0,
+                Modular.add(Long.MAX_VALUE/2, Long.MAX_VALUE/2 + 1, Long.MAX_VALUE));
+
+        assertEquals(0,
+                Modular.add(-1000, -10000000, 10));
+
+        try {
+            Modular.add(1, 1,0);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+    }
+
+    @Test
+    public void subtractTest() {
+        assertEquals(0,
+                Modular.subtract(-22, 3, 5));
+
+        assertEquals(Long.MAX_VALUE-1,
+                Modular.subtract(Long.MAX_VALUE-2, Long.MAX_VALUE-1, Long.MAX_VALUE));
+
+        assertEquals(Long.MAX_VALUE-1,
+                Modular.subtract(1-Long.MAX_VALUE, 2, Long.MAX_VALUE));
+
+        assertEquals(0,
+                Modular.subtract(-1000, -10000000, 10));
+
+        try {
+            Modular.subtract(1, 1,0);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+    }
+
+    @Test
+    public void multiplyTest() {
+        assertEquals(10,
+                Modular.multiply(Long.MAX_VALUE-2, Long.MAX_VALUE-5, Long.MAX_VALUE));
+
+        assertEquals(3,
+                Modular.multiply(-5, -7, 32));
+
+        try {
+            Modular.multiply(1, 1,0);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+
+    }
+
+    @Test
+    public void powerTest() {
+        assertEquals(1,
+                Modular.pow(3, 1000000006, 1000000007));
+
+        assertEquals(8,
+                Modular.pow(2, 66, Long.MAX_VALUE));
+
+        assertEquals(1,
+                Modular.pow(123, 0, 1111));
+
+        assertEquals(0,
+                Modular.pow(0, 123, 2));
+
+        try {
+            Modular.pow(5, 0,5);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+
+        try {
+            Modular.pow(5, -5,5);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+
+        try {
+            Modular.pow(5, 5,0);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+    }
+
+    @Test
+    public void divideTest() {
+        try {
+            Modular.divide(11, 6, 120);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+
+        try {
+            Modular.divide(2, 2, 0);
+            assertTrue("No exception", false);
+        } catch (Exception ignored) {
+        }
+
+        assertEquals(1,
+                Modular.divide(7, 7, 125));
+
+        assertEquals(97,
+                Modular.divide(Modular.multiply(97, 25, 1023), 25, 1023));
+
+        assertEquals(Long.MAX_VALUE-11,
+                Modular.divide(Modular.multiply(Long.MAX_VALUE-11, Long.MAX_VALUE-12, Long.MAX_VALUE),
+                        Long.MAX_VALUE-12,
+                        Long.MAX_VALUE));
+    }
+}