diff --git a/src/test/java/seedu/address/logic/commands/DeleteCommandTest.java b/src/test/java/seedu/address/logic/commands/DeleteCommandTest.java
index f40979b9e57..9e33a96bd61 100644
--- a/src/test/java/seedu/address/logic/commands/DeleteCommandTest.java
+++ b/src/test/java/seedu/address/logic/commands/DeleteCommandTest.java
@@ -1,5 +1,6 @@
 package seedu.address.logic.commands;
 
+import static java.util.Objects.requireNonNull;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -11,6 +12,7 @@
 import static seedu.address.testutil.TypicalModules.getTypicalModuleData;
 import static seedu.address.testutil.TypicalModules.getTypicalModulePlan;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 
 import org.junit.jupiter.api.Test;
@@ -21,9 +23,9 @@
 import seedu.address.model.UserPrefs;
 import seedu.address.model.module.Module;
 import seedu.address.model.module.ModuleCode;
+import seedu.address.model.module.exceptions.DuplicateModuleException;
 import seedu.address.model.module.exceptions.ModuleNotFoundException;
-import seedu.address.testutil.ModelStubAcceptingModuleAdded;
-import seedu.address.testutil.ModelStubWithModule;
+import seedu.address.testutil.ModelStub;
 import seedu.address.testutil.ModuleBuilder;
 import seedu.address.testutil.TypicalModules;
 
@@ -59,7 +61,7 @@ public void execute_moduleAcceptedByModel_deleteSuccessful() {
     @Test
     public void execute_moduleInDataAndInPlan_deleteSuccessful() throws Exception {
         //In both ModuleData and ModulePlan -> Success
-        ModelStubAcceptingModuleAdded modelStub = new ModelStubAcceptingModuleAdded();
+        ModelStubAcceptingModuleAddedAndDelete modelStub = new ModelStubAcceptingModuleAddedAndDelete();
         modelStub.addModule(CS2030S);
         Module validModule = modelStub.getModuleFromDb(CS2030S.getModuleCode());
 
@@ -83,7 +85,7 @@ public void execute_moduleNotInModuleDataNotInModulePlan_throwsModuleNoteFoundEx
     @Test
     public void execute_missingModule_throwsModuleNotFoundException() {
         //In ModuleData and not in ModulePlan -> Fail
-        ModelStubAcceptingModuleAdded modelStub = new ModelStubAcceptingModuleAdded();
+        ModelStubAcceptingModuleAddedAndDelete modelStub = new ModelStubAcceptingModuleAddedAndDelete();
         modelStub.addModule(CS2100);
         Module validModule = modelStub.getModuleFromDb(CS2030S.getModuleCode());
 
@@ -126,4 +128,92 @@ public void toStringMethod() {
         String expected = DeleteCommand.class.getCanonicalName() + "{toDelete=" + code + "}";
         assertEquals(expected, deleteCommand.toString());
     }
+
+    /**
+     * A Model stub that contains a single module.
+     */
+    private class ModelStubWithModule extends ModelStub {
+        private final Module module;
+
+        /**
+         * Initializes a ModelStubWithModule with the given module.
+         *
+         * @param module The module to be associated with the ModelStubWithModule.
+         */
+        ModelStubWithModule(Module module) {
+            requireNonNull(module);
+            this.module = module;
+        }
+
+        @Override
+        public boolean hasModule(Module module) {
+            requireNonNull(module);
+            return this.module.isSameModule(module);
+        }
+
+        @Override
+        public boolean checkDbValidModuleCode(ModuleCode moduleCode) {
+            return getTypicalModuleData().checkDbValidModuleCode(moduleCode);
+        }
+
+        @Override
+        public Module getModuleFromDb(ModuleCode moduleCode) {
+            return getTypicalModuleData().getModule(moduleCode);
+        }
+    }
+
+    /**
+     * A Model stub that always accept the module being added.
+     */
+    private class ModelStubAcceptingModuleAddedAndDelete extends ModelStub {
+        private final ArrayList<Module> modulesAdded = new ArrayList<>();
+
+        @Override
+        public void addModule(Module module) {
+            requireNonNull(module);
+            if (modulesAdded.contains(module)) {
+                throw new DuplicateModuleException();
+            }
+            modulesAdded.add(module);
+        }
+
+        @Override
+        public Module getModule(ModuleCode code) {
+            requireNonNull(code);
+            for (int i = 0; i < modulesAdded.size(); i++) {
+                if (modulesAdded.get(i).getModuleCode().equals(code)) {
+                    return modulesAdded.get(i);
+                }
+            }
+            return null;
+        }
+
+        @Override
+        public void deleteModule(Module module) {
+            if (!modulesAdded.contains(module)) {
+                throw new ModuleNotFoundException();
+            }
+            modulesAdded.remove(module);
+        }
+
+        @Override
+        public boolean hasModule(Module module) {
+            requireNonNull(module);
+            return modulesAdded.stream().anyMatch(module::isSameModule);
+        }
+
+        @Override
+        public boolean checkDbValidModuleCode(ModuleCode moduleCode) {
+            return getTypicalModuleData().checkDbValidModuleCode(moduleCode);
+        }
+
+        @Override
+        public Module getModuleFromDb(ModuleCode moduleCode) {
+            return getTypicalModuleData().getModule(moduleCode);
+        }
+
+        public ArrayList<Module> getModulesAdded() {
+            return this.modulesAdded;
+        }
+    }
 }
diff --git a/src/test/java/seedu/address/testutil/ModelStub.java b/src/test/java/seedu/address/testutil/ModelStub.java
index d19703dd2fc..e4e0baca836 100644
--- a/src/test/java/seedu/address/testutil/ModelStub.java
+++ b/src/test/java/seedu/address/testutil/ModelStub.java
@@ -1,7 +1,5 @@
 package seedu.address.testutil;
 
-import static seedu.address.testutil.TypicalModules.getTypicalModuleData;
-
 import java.nio.file.Path;
 
 import javafx.collections.ObservableList;
@@ -110,11 +108,12 @@ public boolean checkDbValidModule(Module module) {
 
     @Override
     public boolean checkDbValidModuleCode(ModuleCode moduleCode) {
-        return getTypicalModuleData().checkDbValidModuleCode(moduleCode);
+        throw new AssertionError("This method should not be called.");
     }
+
     @Override
     public Module getModuleFromDb(ModuleCode moduleCode) {
-        return getTypicalModuleData().getModule(moduleCode);
+        throw new AssertionError("This method should not be called.");
     }
 
     @Override
diff --git a/src/test/java/seedu/address/testutil/ModelStubAcceptingModuleAdded.java b/src/test/java/seedu/address/testutil/ModelStubAcceptingModuleAdded.java
deleted file mode 100644
index 4e39d2437d0..00000000000
--- a/src/test/java/seedu/address/testutil/ModelStubAcceptingModuleAdded.java
+++ /dev/null
@@ -1,55 +0,0 @@
-package seedu.address.testutil;
-
-import static java.util.Objects.requireNonNull;
-
-import java.util.ArrayList;
-
-import seedu.address.model.module.Module;
-import seedu.address.model.module.ModuleCode;
-import seedu.address.model.module.exceptions.DuplicateModuleException;
-import seedu.address.model.module.exceptions.ModuleNotFoundException;
-
-/**
- * A Model stub that always accept the module being added.
- */
-public class ModelStubAcceptingModuleAdded extends ModelStub {
-    private final ArrayList<Module> modulesAdded = new ArrayList<>();
-
-    @Override
-    public void addModule(Module module) {
-        requireNonNull(module);
-        if (modulesAdded.contains(module)) {
-            throw new DuplicateModuleException();
-        }
-        modulesAdded.add(module);
-    }
-
-    @Override
-    public Module getModule(ModuleCode code) {
-        requireNonNull(code);
-        for (int i = 0; i < modulesAdded.size(); i++) {
-            if (modulesAdded.get(i).getModuleCode().equals(code)) {
-                return modulesAdded.get(i);
-            }
-        }
-        return null;
-    }
-
-    @Override
-    public void deleteModule(Module module) {
-        if (!modulesAdded.contains(module)) {
-            throw new ModuleNotFoundException();
-        }
-        modulesAdded.remove(module);
-    }
-
-    @Override
-    public boolean hasModule(Module module) {
-        requireNonNull(module);
-        return modulesAdded.stream().anyMatch(module::isSameModule);
-    }
-
-    public ArrayList<Module> getModulesAdded() {
-        return this.modulesAdded;
-    }
-}
diff --git a/src/test/java/seedu/address/testutil/ModelStubWithModule.java b/src/test/java/seedu/address/testutil/ModelStubWithModule.java
deleted file mode 100644
index 13d932c5d71..00000000000
--- a/src/test/java/seedu/address/testutil/ModelStubWithModule.java
+++ /dev/null
@@ -1,28 +0,0 @@
-package seedu.address.testutil;
-
-import static java.util.Objects.requireNonNull;
-
-import seedu.address.model.module.Module;
-
-/**
- * A Model stub that contains a single module.
- */
-public class ModelStubWithModule extends ModelStub {
-    private final Module module;
-
-    /**
-     * Initializes a ModelStubWithModule with the given module.
-     *
-     * @param module The module to be associated with the ModelStubWithModule.
-     */
-    public ModelStubWithModule(Module module) {
-        requireNonNull(module);
-        this.module = module;
-    }
-
-    @Override
-    public boolean hasModule(Module module) {
-        requireNonNull(module);
-        return this.module.isSameModule(module);
-    }
-}