Added int and long Operator Test

core-java/functional-programming/functional-interfaces/src/test/java/io/reflectoring/function/OperatorTest.java

@@ -0,0 +1,57 @@
+package io.reflectoring.function;
+
+import java.util.function.Function;
+import java.util.function.IntUnaryOperator;
+import java.util.function.LongUnaryOperator;
+import java.util.function.UnaryOperator;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class OperatorTest {
+  @Test
+  void unaryOperator() {
+    UnaryOperator<String> trim = value -> value == null ? null : value.trim();
+    UnaryOperator<String> upperCase = value -> value == null ? null : value.toUpperCase();
+    Function<String, String> transform = trim.andThen(upperCase);
+
+    Assertions.assertEquals("joy", trim.apply("  joy "));
+    Assertions.assertEquals("  JOY ", upperCase.apply("  joy "));
+    Assertions.assertEquals("JOY", transform.apply("  joy "));
+  }
+
+  @Test
+  void intUnaryOperator() {
+    // formula y = x^2 + 2x + 1
+    IntUnaryOperator formula = x -> (x * x) + (2 * x) + 1;
+    Assertions.assertEquals(36, formula.applyAsInt(5));
+
+    IntStream input = IntStream.of(2, 3, 4);
+    final int[] result = input.map(formula).toArray();
+    Assertions.assertArrayEquals(new int[] {9, 16, 25}, result);
+
+    // the population doubling every 3 years, one fifth migrate and 10% mortality
+    IntUnaryOperator growth = number -> number * 2;
+    IntUnaryOperator migration = number -> number * 4 / 5;
+    IntUnaryOperator mortality = number -> number * 9 / 10;
+    IntUnaryOperator population = growth.andThen(migration).andThen(mortality);
+    Assertions.assertEquals(1440000, population.applyAsInt(1000000));
+  }
+
+  @Test
+  void longUnaryOperator() {
+    // light travels 186282 miles per seconds
+    LongUnaryOperator distance = time -> time * 186282;
+    // denser medium slows light down
+    LongUnaryOperator slowDown = dist -> dist * 2 / 3;
+    LongUnaryOperator actualDistance = distance.andThen(slowDown);
+
+    Assertions.assertEquals(931410, distance.applyAsLong(5));
+    Assertions.assertEquals(620940, actualDistance.applyAsLong(5));
+
+    final LongStream input = LongStream.of(5, 10, 15);
+    final long[] result = input.map(distance).toArray();
+    Assertions.assertArrayEquals(new long[] {931410L, 1862820L, 2794230L}, result);
+  }
+}