Add unit tests for SyncStack, verifying JSON handling with various scenarios including all fields, pagination and sync tokens, and null input handling to enhance test coverage and ensure correct behavior.

Author: harshithad0703

contentstack/src/test/java/com/contentstack/sdk/TestSyncStack.java

@@ -0,0 +1,114 @@
+package com.contentstack.sdk;
+
+import org.json.JSONArray;
+import org.json.JSONObject;
+import org.junit.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.Assert.*;
+
+public class TestSyncStack {
+
+    @Test
+    public void testSetJSON_withAllFields() throws Exception {
+        // Build JSON with all properties
+        JSONObject json = new JSONObject();
+        json.put("skip", 5);
+        json.put("total_count", 100);
+        json.put("limit", 20);
+        json.put("pagination_token", "page_token_value");
+        json.put("sync_token", "sync_token_value");
+
+        JSONArray items = new JSONArray();
+        JSONObject item1 = new JSONObject();
+        item1.put("uid", "1");
+        items.put(item1);
+        JSONObject item2 = new JSONObject();
+        item2.put("uid", "2");
+        items.put(item2);
+        json.put("items", items);
+
+        SyncStack syncStack = new SyncStack();
+        syncStack.setJSON(json);
+
+        // URL should be set to empty string in setJSON
+        assertEquals("", syncStack.getURL());
+
+        // verify basic numeric fields
+        assertEquals(5, syncStack.getSkip());
+        assertEquals(100, syncStack.getCount());
+        assertEquals(20, syncStack.getLimit());
+
+        // verify tokens
+        assertEquals("page_token_value", syncStack.getPaginationToken());
+        assertEquals("sync_token_value", syncStack.getSyncToken());
+
+        // verify items
+        ArrayList<JSONObject> resultItems = syncStack.getItems();
+        assertNotNull(resultItems);
+        assertEquals(2, resultItems.size());
+        assertEquals("1", resultItems.get(0).optString("uid"));
+        assertEquals("2", resultItems.get(1).optString("uid"));
+
+        // verify JSON response stored
+        assertNotNull(syncStack.getJSONResponse());
+        assertEquals(json.toString(), syncStack.getJSONResponse().toString());
+    }
+
+    @Test
+    public void testSetJSON_onlyPaginationToken() throws Exception {
+        JSONObject json = new JSONObject();
+        json.put("skip", 0);
+        json.put("total_count", 10);
+        json.put("limit", 10);
+        json.put("pagination_token", "only_pagination");
+
+        SyncStack syncStack = new SyncStack();
+        syncStack.setJSON(json);
+
+        assertEquals(0, syncStack.getSkip());
+        assertEquals(10, syncStack.getCount());
+        assertEquals(10, syncStack.getLimit());
+        assertEquals("only_pagination", syncStack.getPaginationToken());
+        // because has("sync_token") == false, sync_token should be null
+        assertNull(syncStack.getSyncToken());
+    }
+
+    @Test
+    public void testSetJSON_onlySyncToken() throws Exception {
+        JSONObject json = new JSONObject();
+        json.put("skip", 1);
+        json.put("total_count", 5);
+        json.put("limit", 5);
+        json.put("sync_token", "only_sync");
+
+        SyncStack syncStack = new SyncStack();
+        syncStack.setJSON(json);
+
+        assertEquals(1, syncStack.getSkip());
+        assertEquals(5, syncStack.getCount());
+        assertEquals(5, syncStack.getLimit());
+
+        // no pagination_token present
+        assertNull(syncStack.getPaginationToken());
+        assertEquals("only_sync", syncStack.getSyncToken());
+    }
+
+    @Test
+    public void testSetJSON_nullDoesNothing() {
+        SyncStack syncStack = new SyncStack();
+        // should simply not throw and not change fields
+        syncStack.setJSON(null);
+
+        // all getters should remain default (null / 0)
+        assertNull(syncStack.getJSONResponse());
+        assertNull(syncStack.getURL());
+        assertEquals(0, syncStack.getSkip());
+        assertEquals(0, syncStack.getCount());
+        assertEquals(0, syncStack.getLimit());
+        assertNull(syncStack.getPaginationToken());
+        assertNull(syncStack.getSyncToken());
+        assertNull(syncStack.getItems());
+    }
+}