diff --git a/app/src/test/java/com/example/cosmosclient/Component.java b/app/src/test/java/com/example/cosmosclient/Component.java
new file mode 100644
index 0000000..e831836
--- /dev/null
+++ b/app/src/test/java/com/example/cosmosclient/Component.java
@@ -0,0 +1,25 @@
+package com.example.cosmosclient;
+
+public class Component {
+    private String id;
+
+    public Component() {
+    }
+
+    public Component(String id) {
+        this.id = id;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public boolean equals(Object other) {
+        if (!(other instanceof Component)) return false;
+        return id.equals(((Component)other).id);
+    }
+}
diff --git a/app/src/test/java/com/example/cosmosclient/Container.java b/app/src/test/java/com/example/cosmosclient/Container.java
new file mode 100644
index 0000000..ec49ea4
--- /dev/null
+++ b/app/src/test/java/com/example/cosmosclient/Container.java
@@ -0,0 +1,40 @@
+package com.example.cosmosclient;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+
+import java.util.ArrayList;
+
+public class Container {
+    private ArrayList<Component> components = new ArrayList<>();
+
+    public ArrayList<Component> getComponents() {
+        return components;
+    }
+
+    public void setComponents(ArrayList<Component> components) {
+        this.components = components;
+    }
+
+    public void addComponent(Component c) {
+        components.add(c);
+    }
+
+    public Component getComponent(int index) {
+        return components.get(index);
+    }
+
+    public void removeComponent(int index) {
+        components.remove(index);
+    }
+
+    @JsonIgnore
+    public int getComponentsCount() {
+        return components.size();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof Container)) return false;
+        return components.equals(((Container)other).components);
+    }
+}
diff --git a/app/src/test/java/com/example/cosmosclient/Container2.java b/app/src/test/java/com/example/cosmosclient/Container2.java
new file mode 100644
index 0000000..30edbba
--- /dev/null
+++ b/app/src/test/java/com/example/cosmosclient/Container2.java
@@ -0,0 +1,41 @@
+package com.example.cosmosclient;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+
+public class Container2 {
+    private HashMap<String, Component> components = new HashMap<>();
+
+    public HashMap<String, Component> getComponents() {
+        return components;
+    }
+
+    public void setComponents(HashMap<String, Component> components) {
+        this.components = components;
+    }
+
+    public void putComponent(String key, Component c) {
+        components.put(key, c);
+    }
+
+    public Component getComponent(int index) {
+        return components.get(index);
+    }
+
+    public void removeComponent(int index) {
+        components.remove(index);
+    }
+
+    @JsonIgnore
+    public int getComponentsCount() {
+        return components.size();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof Container2)) return false;
+        return components.equals(((Container2)other).components);
+    }
+}
diff --git a/app/src/test/java/com/example/cosmosclient/JacksonTest.java b/app/src/test/java/com/example/cosmosclient/JacksonTest.java
new file mode 100644
index 0000000..d4c9efd
--- /dev/null
+++ b/app/src/test/java/com/example/cosmosclient/JacksonTest.java
@@ -0,0 +1,55 @@
+package com.example.cosmosclient;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class JacksonTest {
+    @Test
+    public void jacksonTest() {
+        Container srcContainer = new Container();
+        srcContainer.addComponent(new Component("A"));
+        srcContainer.addComponent(new Component("B"));
+        srcContainer.addComponent(new Component("C"));
+        ObjectMapper om = new ObjectMapper();
+        try {
+            String containerJSON = om.writeValueAsString(srcContainer);
+            System.out.println(containerJSON);
+
+            ObjectMapper mo = new ObjectMapper();
+            Container dstContainer = mo.readValue(containerJSON, Container.class);
+
+            System.out.println(om.writeValueAsString(dstContainer));
+            assertEquals(srcContainer, dstContainer);
+        } catch (JsonProcessingException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        Container2 srcContainer2 = new Container2();
+        srcContainer2.putComponent("X", new Component("A"));
+        srcContainer2.putComponent("Y", new Component("B"));
+        srcContainer2.putComponent("Z", new Component("C"));
+        ObjectMapper om2 = new ObjectMapper();
+        try {
+            String containerJSON2 = om2.writeValueAsString(srcContainer2);
+            System.out.println(containerJSON2);
+
+            ObjectMapper mo2 = new ObjectMapper();
+            Container2 dstContainer2 = mo2.readValue(containerJSON2, Container2.class);
+
+            System.out.println(om2.writeValueAsString(dstContainer2));
+            assertEquals(srcContainer2, dstContainer2);
+        } catch (JsonProcessingException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}