diff --git a/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java b/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java
new file mode 100644
index 0000000000..9e8080a3b3
--- /dev/null
+++ b/guava/src/test/java/org/baeldung/guava/GuavaPreConditionsTest.java
@@ -0,0 +1,141 @@
+package org.baeldung.guava;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import java.util.Arrays;
+import org.junit.Test;
+import static com.google.common.base.Preconditions.*;
+
+public class GuavaPreConditionsTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void whenCheckArgumentEvaluatesFalse_throwsException() {
+        int age = -18;
+        checkArgument(age > 0);
+    }
+
+    @Test
+    public void givenErrorMessage_whenCheckArgumentEvaluatesFalse_throwsException() {
+        final int age = -18;
+        final String message = "Age can't be zero or less than zero";
+        try {
+            checkArgument(age > 0, message);
+        } catch (IllegalArgumentException illegalArgumentException) {
+            assertEquals(message, illegalArgumentException.getMessage());
+        }
+    }
+
+    @Test
+    public void givenTemplatedErrorMessage_whenCheckArgumentEvaluatesFalse_throwsException() {
+        final int age = -18;
+        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());
+        }
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void givenArrayOfIntegers_whenCheckElementIndexEvaluatesFalse_throwsException() {
+        final int[] numbers = { 1, 2, 3, 4, 5 };
+        checkElementIndex(6, numbers.length - 1);
+    }
+
+    @Test
+    public void givenArrayOfIntegersAndMessage_whenCheckElementIndexEvaluatesFalse_throwsException() {
+        final int[] numbers = { 1, 2, 3, 4, 5 };
+        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));
+        }
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_whenCheckNotNullCalled_throwsException() {
+        final String nullObject = null;
+        checkNotNull(nullObject);
+    }
+
+    @Test
+    public void givenNullString_whenCheckNotNullCalledWithMessage_throwsException() {
+        final String nullObject = null;
+        final String message = "Please check the Object supplied, its null!";
+        try {
+            checkNotNull(nullObject, message);
+        } catch (NullPointerException nullPointerException) {
+            assertEquals(message, nullPointerException.getMessage());
+        }
+    }
+
+    @Test
+    public void givenNullString_whenCheckNotNullCalledWithTemplatedMessage_throwsException() {
+        final String nullObject = null;
+        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());
+        }
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void givenArrayOfIntegers_whenCheckPositionIndexEvaluatesFalse_throwsException() {
+        final int[] numbers = { 1, 2, 3, 4, 5 };
+        checkPositionIndex(6, numbers.length - 1);
+    }
+
+    @Test
+    public void givenArrayOfIntegersAndMessage_whenCheckPositionIndexEvaluatesFalse_throwsException() {
+        final int[] numbers = { 1, 2, 3, 4, 5 };
+        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));
+        }
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void givenArrayOfIntegers_whenCheckPositionIndexesEvaluatesFalse_throwsException() {
+        final int[] numbers = { 1, 2, 3, 4, 5 };
+        checkPositionIndexes(6, 0, numbers.length - 1);
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void givenValidStates_whenCheckStateEvaluatesFalse_throwsException() {
+        final int[] validStates = { -1, 0, 1 };
+        final int givenState = 10;
+        checkState(Arrays.binarySearch(validStates, givenState) > 0);
+    }
+
+    @Test
+    public void givenValidStatesAndMessage_whenCheckStateEvaluatesFalse_throwsException() {
+        final int[] validStates = { -1, 0, 1 };
+        final int givenState = 10;
+        final String message = "You have entered an invalid state";
+        try {
+            checkState(Arrays.binarySearch(validStates, givenState) < 0, message);
+        } catch (IllegalStateException IllegalStateException) {
+            assertEquals(message, IllegalStateException.getMessage());
+        }
+    }
+
+    @Test
+    public void givenValidStatesAndTemplatedMessage_whenCheckStateEvaluatesFalse_throwsException() {
+        final int[] validStates = { -1, 0, 1 };
+        final int givenState = 10;
+        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());
+        }
+    }
+
+}