BAEL-3597 Cactoos (#8512)

* BAEL-3597 Cactoos

* BAEL-3597 Cactoos

* BAEL-3597 Cactoos

* BAEL-3597 Cactoos

libraries-3/src/test/java/com/baeldung/cactoos/CactoosCollectionUtilsUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.cactoos;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.ArrayList;
+
+import org.junit.Test;
+
+public class CactoosCollectionUtilsUnitTest {
+
+	@Test
+	public void whenFilteredClassIsCalledWithSpecificArgs_thenCorrespondingFilteredCollectionShouldBeReturned() throws IOException {
+
+		CactoosCollectionUtils obj = new CactoosCollectionUtils();
+
+		// when
+		List<String> strings = new ArrayList<String>() { 
+            { 
+                add("Hello"); 
+                add("John"); 
+                add("Smith"); 
+                add("Eric");
+                add("Dizzy");
+            } 
+        }; 
+		int size = obj.getFilteredList(strings).size();
+
+		// then
+		assertEquals(3, size);
+
+	}
+
+}

libraries-3/src/test/java/com/baeldung/cactoos/CactoosStringUtilsUnitTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.cactoos;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+public class CactoosStringUtilsUnitTest {
+
+	@Test
+	public void whenFormattedTextIsPassedWithArgs_thenFormattedStringIsReturned() throws IOException {
+
+		CactoosStringUtils obj = new CactoosStringUtils();
+
+		// when
+		String formattedString = obj.createdFormattedString("John");
+
+		// then
+		assertEquals("Hello John", formattedString);
+
+	}
+	
+	@Test
+	public void whenStringIsPassesdToLoweredOrUpperClass_thenCorrespondingStringIsReturned() throws Exception {
+
+		CactoosStringUtils obj = new CactoosStringUtils();
+
+		// when
+		String lowerCaseString = obj.toLowerCase("TeSt StrIng");
+		String upperCaseString = obj.toUpperCase("TeSt StrIng");
+
+		// then
+		assertEquals("test string", lowerCaseString);
+		assertEquals("TEST STRING", upperCaseString);
+
+	}
+	
+	@Test
+	public void whenEmptyStringIsPassesd_thenIsBlankReturnsTrue() throws Exception {
+
+		CactoosStringUtils obj = new CactoosStringUtils();
+
+		// when
+		boolean isBlankEmptyString = obj.isBlank("");
+		boolean isBlankNull = obj.isBlank(null);
+
+		// then
+		assertEquals(true, isBlankEmptyString);
+		assertEquals(true, isBlankNull);
+
+	}
+
+}