diff --git a/guava/pom.xml b/guava/pom.xml
index 0a50fad2c3..f65a9a2081 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -57,6 +57,12 @@
             <scope>test</scope>
         </dependency>
 
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -100,6 +106,7 @@
         <org.hamcrest.version>1.3</org.hamcrest.version>
         <junit.version>4.12</junit.version>
         <mockito.version>1.10.19</mockito.version>
+        <assertj.version>3.6.1</assertj.version>
 
         <!-- maven plugins -->
         <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
diff --git a/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java b/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java
index 9e8080a3b3..b9c1ca3c9d 100644
--- a/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java
+++ b/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java
@@ -1,17 +1,22 @@
 package org.baeldung.guava;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.assertj.core.api.Assertions.assertThat;
 import java.util.Arrays;
 import org.junit.Test;
 import static com.google.common.base.Preconditions.*;
 
 public class GuavaPreConditionsTest {
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void whenCheckArgumentEvaluatesFalse_throwsException() {
         int age = -18;
-        checkArgument(age > 0);
+        try {
+            checkArgument(age > 0);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalArgumentException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(null);
+        }
     }
 
     @Test
@@ -20,8 +25,10 @@ public class GuavaPreConditionsTest {
         final String message = "Age can't be zero or less than zero";
         try {
             checkArgument(age > 0, message);
-        } catch (IllegalArgumentException illegalArgumentException) {
-            assertEquals(message, illegalArgumentException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalArgumentException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message);
         }
     }
 
@@ -31,16 +38,22 @@ public class GuavaPreConditionsTest {
         final String message = "Age can't be zero or less than zero, you supplied %s.";
         try {
             checkArgument(age > 0, message, age);
-        } catch (IllegalArgumentException illegalArgumentException) {
-            final String formattedMessage = String.format(message, age);
-            assertEquals(formattedMessage, illegalArgumentException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalArgumentException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message, age);
         }
     }
 
-    @Test(expected = IndexOutOfBoundsException.class)
+    @Test
     public void givenArrayOfIntegers_whenCheckElementIndexEvaluatesFalse_throwsException() {
         final int[] numbers = { 1, 2, 3, 4, 5 };
-        checkElementIndex(6, numbers.length - 1);
+        try {
+            checkElementIndex(6, numbers.length - 1);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IndexOutOfBoundsException.class);
+            assertThat(exception).hasNoCause();
+        }
     }
 
     @Test
@@ -49,15 +62,23 @@ public class GuavaPreConditionsTest {
         final String message = "Please check the bound of an array and retry";
         try {
             checkElementIndex(6, numbers.length - 1, message);
-        } catch (IndexOutOfBoundsException indexOutOfBoundsException) {
-            assertTrue(indexOutOfBoundsException.getMessage().startsWith(message));
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IndexOutOfBoundsException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception.getMessage()).startsWith(message);
         }
     }
 
-    @Test(expected = NullPointerException.class)
+    @Test
     public void givenNullString_whenCheckNotNullCalled_throwsException() {
         final String nullObject = null;
-        checkNotNull(nullObject);
+        try {
+            checkNotNull(nullObject);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(NullPointerException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(null);
+        }
     }
 
     @Test
@@ -66,8 +87,10 @@ public class GuavaPreConditionsTest {
         final String message = "Please check the Object supplied, its null!";
         try {
             checkNotNull(nullObject, message);
-        } catch (NullPointerException nullPointerException) {
-            assertEquals(message, nullPointerException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(NullPointerException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message);
         }
     }
 
@@ -77,16 +100,22 @@ public class GuavaPreConditionsTest {
         final String message = "Please check the Object supplied, its %s!";
         try {
             checkNotNull(nullObject, message, nullObject);
-        } catch (NullPointerException nullPointerException) {
-            final String formattedMessage = String.format(message, nullObject);
-            assertEquals(formattedMessage, nullPointerException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(NullPointerException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message, nullObject);
         }
     }
 
-    @Test(expected = IndexOutOfBoundsException.class)
+    @Test
     public void givenArrayOfIntegers_whenCheckPositionIndexEvaluatesFalse_throwsException() {
         final int[] numbers = { 1, 2, 3, 4, 5 };
-        checkPositionIndex(6, numbers.length - 1);
+        try {
+            checkPositionIndex(6, numbers.length - 1);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IndexOutOfBoundsException.class);
+            assertThat(exception).hasNoCause();
+        }
     }
 
     @Test
@@ -95,22 +124,35 @@ public class GuavaPreConditionsTest {
         final String message = "Please check the bound of an array and retry";
         try {
             checkPositionIndex(6, numbers.length - 1, message);
-        } catch (IndexOutOfBoundsException indexOutOfBoundsException) {
-            assertTrue(indexOutOfBoundsException.getMessage().startsWith(message));
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IndexOutOfBoundsException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception.getMessage()).startsWith(message);
         }
     }
 
-    @Test(expected = IndexOutOfBoundsException.class)
+    @Test
     public void givenArrayOfIntegers_whenCheckPositionIndexesEvaluatesFalse_throwsException() {
         final int[] numbers = { 1, 2, 3, 4, 5 };
-        checkPositionIndexes(6, 0, numbers.length - 1);
+        try {
+            checkPositionIndexes(6, 0, numbers.length - 1);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IndexOutOfBoundsException.class);
+            assertThat(exception).hasNoCause();
+        }
     }
 
-    @Test(expected = IllegalStateException.class)
+    @Test
     public void givenValidStates_whenCheckStateEvaluatesFalse_throwsException() {
         final int[] validStates = { -1, 0, 1 };
         final int givenState = 10;
-        checkState(Arrays.binarySearch(validStates, givenState) > 0);
+        try {
+            checkState(Arrays.binarySearch(validStates, givenState) > 0);
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalStateException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(null);
+        }
     }
 
     @Test
@@ -120,8 +162,10 @@ public class GuavaPreConditionsTest {
         final String message = "You have entered an invalid state";
         try {
             checkState(Arrays.binarySearch(validStates, givenState) < 0, message);
-        } catch (IllegalStateException IllegalStateException) {
-            assertEquals(message, IllegalStateException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalStateException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message);
         }
     }
 
@@ -132,10 +176,11 @@ public class GuavaPreConditionsTest {
         final String message = "State can't be %s, It can be one of %s.";
         try {
             checkState(Arrays.binarySearch(validStates, givenState) < 0, message, givenState, Arrays.toString(validStates));
-        } catch (IllegalStateException IllegalStateException) {
-            final String formattedMessage = String.format(message, givenState, Arrays.toString(validStates));
-            assertEquals(formattedMessage, IllegalStateException.getMessage());
+        } catch (Exception exception) {
+            assertThat(exception).isInstanceOf(IllegalStateException.class);
+            assertThat(exception).hasNoCause();
+            assertThat(exception).hasMessage(message, givenState, Arrays.toString(validStates));
         }
     }
 
-}
+}
\ No newline at end of file