BAEL-5970 Working with MathFlux (#15116)

* Working with MathFlux.

* revert change to readme.

* merge codes in unit test.

* merge codes in unit test.

---------

Co-authored-by: rezaganjis <Ganji@tosan.com>

reactor-core/pom.xml

@@ -26,6 +26,11 @@
             <version>${reactor.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.projectreactor.addons</groupId>
+            <artifactId>reactor-extra</artifactId>
+            <version>${reactor.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
@@ -35,7 +40,7 @@
     </dependencies>
 
     <properties>
-        <reactor.version>3.4.17</reactor.version>
+        <reactor.version>3.5.1</reactor.version>
     </properties>
 
 </project>

reactor-core/src/test/java/com/baeldung/reactor/math/MathFluxOperationsUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.math;
+
+import org.junit.Test;
+
+import reactor.math.MathFlux;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+public class MathFluxOperationsUnitTest {
+
+    @Test
+    public void givenFluxOfNumbers_whenCalculatingSum_thenExpectCorrectResult() {
+        Flux<Integer> numbers = Flux.just(1, 2, 3, 4, 5);
+        Mono<Integer> sumMono = MathFlux.sumInt(numbers);
+        StepVerifier.create(sumMono)
+          .expectNext(15)
+          .verifyComplete();
+    }
+
+    @Test
+    public void givenFluxOfNumbers_whenCalculatingAverage_thenExpectCorrectResult() {
+        Flux<Integer> numbers = Flux.just(1, 2, 3, 4, 5);
+        Mono<Double> averageMono = MathFlux.averageDouble(numbers);
+        StepVerifier.create(averageMono)
+          .expectNext(3.0)
+          .verifyComplete();
+    }
+
+    @Test
+    public void givenFluxOfNumbers_whenFindingMinElement_thenExpectCorrectResult() {
+        Flux<Integer> numbers = Flux.just(3, 1, 5, 2, 4);
+        Mono<Integer> minMono = MathFlux.min(numbers);
+        StepVerifier.create(minMono)
+          .expectNext(1)
+          .verifyComplete();
+    }
+
+    @Test
+    public void givenFluxOfNumbers_whenFindingMaxElement_thenExpectCorrectResult() {
+        Flux<Integer> numbers = Flux.just(3, 1, 5, 2, 4);
+        Mono<Integer> maxMono = MathFlux.max(numbers);
+        StepVerifier.create(maxMono)
+          .expectNext(5)
+          .verifyComplete();
+    }
+
+}