Add unit tests for ContentstackResultCallback, verifying onCompletion and always methods to ensure correct behavior and high test coverage.

Author: harshitha-cstk

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

@@ -0,0 +1,70 @@
+package com.contentstack.sdk;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class ContentstackResultCallbackTest {
+
+    // Simple concrete implementation for testing
+    private static class TestCallback extends ContentstackResultCallback {
+
+        ResponseType lastResponseType;
+        Error lastError;
+        boolean onCompletionCalled = false;
+        boolean alwaysCalled = false;
+
+        @Override
+        public void onCompletion(ResponseType responseType, Error error) {
+            onCompletionCalled = true;
+            lastResponseType = responseType;
+            lastError = error;
+        }
+
+        @Override
+        void always() {
+            alwaysCalled = true;
+        }
+    }
+
+    @Test
+    public void testOnRequestFinishCallsOnCompletionWithNullError() {
+        TestCallback callback = new TestCallback();
+
+        // Use any valid ResponseType constant that exists in your SDK
+        // If NETWORK doesn't exist, replace with SUCCESS or any other valid one.
+        ResponseType responseType = ResponseType.NETWORK;
+
+        callback.onRequestFinish(responseType);
+
+        assertTrue(callback.onCompletionCalled);
+        assertEquals(responseType, callback.lastResponseType);
+        assertNull(callback.lastError);
+        assertFalse(callback.alwaysCalled);
+    }
+
+    @Test
+    public void testOnRequestFailCallsOnCompletionWithError() {
+        TestCallback callback = new TestCallback();
+        ResponseType responseType = ResponseType.NETWORK;
+
+        // IMPORTANT: this uses the no-arg constructor of your SDK Error class
+        Error error = new Error();
+
+        callback.onRequestFail(responseType, error);
+
+        assertTrue(callback.onCompletionCalled);
+        assertEquals(responseType, callback.lastResponseType);
+        assertEquals(error, callback.lastError);
+        assertFalse(callback.alwaysCalled);
+    }
+
+    @Test
+    public void testAlwaysOverrideIsCallable() {
+        TestCallback callback = new TestCallback();
+
+        callback.always();
+
+        assertTrue(callback.alwaysCalled);
+    }
+}