Added suppliers test.

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

@@ -0,0 +1,59 @@
+package io.reflectoring.function;
+
+import java.util.Random;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.*;
+import java.util.stream.DoubleStream;
+import java.util.stream.LongStream;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+public class SupplierTest {
+  @Test
+  void supplier() {
+    // Supply random numbers
+    Supplier<Integer> randomNumberSupplier = () -> new Random().nextInt(100);
+    int result = randomNumberSupplier.get();
+    Assertions.assertTrue(result >= 0 && result < 100);
+  }
+
+  @Test
+  void intSupplier() {
+    IntSupplier nextWinner = () -> new Random().nextInt(100, 200);
+    int result = nextWinner.getAsInt();
+    Assertions.assertTrue(result >= 100 && result < 200);
+  }
+
+  @Test
+  void longSupplier() {
+    LongSupplier nextWinner = () -> new Random().nextLong(100, 200);
+    LongStream winners = LongStream.generate(nextWinner).limit(10);
+    Assertions.assertEquals(10, winners.toArray().length);
+  }
+
+  @Test
+  void doubleSupplier() {
+    // Random data for plotting graph
+    DoubleSupplier weightSupplier = () -> new Random().nextDouble(100, 200);
+    DoubleStream dataSample = DoubleStream.generate(weightSupplier).limit(10);
+    Assertions.assertEquals(10, dataSample.toArray().length);
+  }
+
+  @ParameterizedTest
+  @CsvSource(value = {"ON,true", "OFF,false"})
+  void booleanSupplier(String statusCode, boolean expected) {
+    AtomicReference<String> status = new AtomicReference<>();
+    status.set(statusCode);
+    // Simulate a service health check
+    BooleanSupplier isServiceHealthy =
+        () -> {
+          // Here, we could check the actual health of a service.
+          // simplified for test purpose
+          return status.toString().equals("ON");
+        };
+    boolean result = isServiceHealthy.getAsBoolean();
+    Assertions.assertEquals(expected, result);
+  }
+}