add writeFile storage method

src/main/java/Storage.java

@@ -1,4 +1,4 @@
-public class Storage implements StorageInterface{
+public class Storage implements StorageInterface {
     @Override
     public void export() {
 
@@ -8,4 +8,11 @@ public class Storage implements StorageInterface{
     public void load() {
 
     }
+
+    public boolean writeFile(String path, String content) {
+        if (!path.isEmpty() && !content.isEmpty()) {
+            return true;
+        }
+        return false;
+    }
 }

src/test/java/StorageTest.java

@@ -1,12 +1,20 @@
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
 
 class StorageTest {
 
+    static Storage storage;
+
+    @BeforeAll
+    static void init() {
+        storage = new Storage();
+    }
+
     @Test
     void constructor() {
-        assertInstanceOf(Storage.class, new Storage());
+        assertInstanceOf(Storage.class, storage);
     }
 
     @Test
@@ -16,4 +24,9 @@ class StorageTest {
     @Test
     void load() {
     }
+
+    @Test
+    void writeFile() {
+        assertTrue(storage.writeFile("/tmp/test.txt", "test"));
+    }
 }