diff --git a/src/main/java/net/thauvin/erik/mobibot/modules/AbstractModule.java b/src/main/java/net/thauvin/erik/mobibot/modules/AbstractModule.java
index 4a8908a..8abafaf 100644
--- a/src/main/java/net/thauvin/erik/mobibot/modules/AbstractModule.java
+++ b/src/main/java/net/thauvin/erik/mobibot/modules/AbstractModule.java
@@ -123,7 +123,7 @@ public abstract class AbstractModule {
      *
      * @return <code>true</code> if the properties are valid, <code>false</code> otherwise.
      */
-    public boolean isValidProperties() {
+    boolean isValidProperties() {
         for (final String s : getPropertyKeys()) {
             if (!Utils.isValidString(properties.get(s))) {
                 return false;
diff --git a/src/main/java/net/thauvin/erik/mobibot/modules/Calc.java b/src/main/java/net/thauvin/erik/mobibot/modules/Calc.java
index 17c3ba9..2c2a513 100644
--- a/src/main/java/net/thauvin/erik/mobibot/modules/Calc.java
+++ b/src/main/java/net/thauvin/erik/mobibot/modules/Calc.java
@@ -49,7 +49,7 @@ public class Calc extends AbstractModule {
     /**
      * The Calc command.
      */
-    public static final String CALC_CMD = "calc";
+    private static final String CALC_CMD = "calc";
 
     /**
      * The default constructor.
@@ -64,7 +64,7 @@ public class Calc extends AbstractModule {
      * @param query The query.
      * @return The calculation result.
      */
-    public static String calc(final String query) {
+    static String calc(final String query) {
         final DecimalFormat decimalFormat = new DecimalFormat("#.##");
 
         try {
diff --git a/src/main/java/net/thauvin/erik/mobibot/modules/Lookup.java b/src/main/java/net/thauvin/erik/mobibot/modules/Lookup.java
index da051c3..3f6d8e2 100644
--- a/src/main/java/net/thauvin/erik/mobibot/modules/Lookup.java
+++ b/src/main/java/net/thauvin/erik/mobibot/modules/Lookup.java
@@ -46,15 +46,13 @@ import java.net.UnknownHostException;
  * @since 1.0
  */
 public final class Lookup extends AbstractModule {
-    /**
-     * The lookup command.
-     */
-    public static final String LOOKUP_CMD = "lookup";
-
     /**
      * The whois default host.
      */
-    public static final String WHOIS_HOST = "whois.arin.net";
+    static final String WHOIS_HOST = "whois.arin.net";
+
+    // The lookup command.
+    private static final String LOOKUP_CMD = "lookup";
 
     /**
      * The default constructor
@@ -72,7 +70,7 @@ public final class Lookup extends AbstractModule {
      */
     public static String lookup(final String query)
         throws UnknownHostException {
-        final StringBuilder buffer = new StringBuilder("");
+        final StringBuilder buffer = new StringBuilder();
 
         final InetAddress[] results = InetAddress.getAllByName(query);
         String hostInfo;
diff --git a/src/test/java/net/thauvin/erik/mobibot/modules/AbstractModuleTest.java b/src/test/java/net/thauvin/erik/mobibot/modules/AbstractModuleTest.java
new file mode 100644
index 0000000..2c2e109
--- /dev/null
+++ b/src/test/java/net/thauvin/erik/mobibot/modules/AbstractModuleTest.java
@@ -0,0 +1,58 @@
+/*
+ * AbstractModuleTest.java
+ *
+ * Copyright (c) 2004-2019, Erik C. Thauvin (erik@thauvin.net)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ *   Neither the name of this project nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.thauvin.erik.mobibot.modules;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * The <code>AbstractModuleTest</code> class.
+ *
+ * @author <a href="https://erik.thauvin.net/" target="_blank">Erik C. Thauvin</a>
+ * @created 2019-04-07
+ * @since 1.0
+ */
+final class AbstractModuleTest {
+    static void testAbstractModule(AbstractModule module) {
+        final String name = module.getClass().getName();
+        assertThat(module.isEnabled()).as(name + ": enabled").isTrue();
+        assertThat(module.getCommands().size()).as(name + ": commands > 0").isGreaterThan(0);
+        if (!module.hasProperties()) {
+            assertThat(module.getPropertyKeys().size()).as(name + ": no properties").isEqualTo(0);
+            module.setProperty("test", "test");
+            module.setProperty("", "invalid");
+        }
+        assertThat(module.getPropertyKeys().size()).as(name + ": properties > 0").isGreaterThan(0);
+        assertThat(module.isValidProperties()).as(name + ": isValidProperties()").isTrue();
+        module.setProperty("invalid", "");
+        assertThat(module.isValidProperties()).as(name + ": invalid properties").isFalse();
+    }
+}
diff --git a/src/test/java/net/thauvin/erik/mobibot/modules/CalcTest.java b/src/test/java/net/thauvin/erik/mobibot/modules/CalcTest.java
index e8726c2..b70450b 100644
--- a/src/test/java/net/thauvin/erik/mobibot/modules/CalcTest.java
+++ b/src/test/java/net/thauvin/erik/mobibot/modules/CalcTest.java
@@ -43,6 +43,11 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @since 1.0
  */
 public class CalcTest {
+    @Test
+    public void testCalcImpl() {
+        AbstractModuleTest.testAbstractModule(new Calc());
+    }
+    
     @Test
     public void testCalc() {
         assertThat(Calc.calc("1 + 1")).as("calc(1+1)").isEqualTo("1+1 = 2");
diff --git a/src/test/java/net/thauvin/erik/mobibot/modules/LookupTest.java b/src/test/java/net/thauvin/erik/mobibot/modules/LookupTest.java
index a2bd651..bd85a7a 100644
--- a/src/test/java/net/thauvin/erik/mobibot/modules/LookupTest.java
+++ b/src/test/java/net/thauvin/erik/mobibot/modules/LookupTest.java
@@ -45,6 +45,11 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @since 1.0
  */
 public class LookupTest {
+    @Test
+    public void testLookupImpl() {
+        AbstractModuleTest.testAbstractModule(new Lookup());
+    }
+
     @Test
     public void testLookup() throws Exception {
         final String result = Lookup.lookup("erik.thauvin.net");