Fix flaky testReadCompactedWithNullValue by waiting for compaction

The test was triggering compaction but reading immediately without
waiting for it to complete. Since compaction is asynchronous, the
reader might read uncompacted data. Added polling of the compaction
status endpoint to wait until compaction completes before reading.

Made-with: Cursor

Author: Bhargavkonidena

tests/ReaderTest.cc

@@ -1069,7 +1069,7 @@ TEST(ReaderTest, testReadCompactedWithNullValue) {
     ASSERT_EQ(ResultOk,
               producer.send(MessageBuilder().setPartitionKey("key1").setContent("value1-updated").build()));
 
-    // Trigger compaction via admin API
+    // Trigger compaction via admin API and wait for it to complete
     {
         // Build compaction URL directly from topicName to avoid mismatches
         // topicName is "persistent://public/default/..." -> need "persistent/public/default/..."
@@ -1081,6 +1081,24 @@ TEST(ReaderTest, testReadCompactedWithNullValue) {
         std::string compactUrl = adminUrl + "admin/v2/" + topicPath + "/compaction";
         int res = makePutRequest(compactUrl, "");
         ASSERT_TRUE(res == 204 || res == 409) << "Failed to trigger compaction, res: " << res;
+
+        // Wait for compaction to complete by polling the status endpoint
+        std::string lastStatus;
+        ASSERT_TRUE(waitUntil(
+            std::chrono::seconds(60),
+            [&compactUrl, &lastStatus]() {
+                std::string responseData;
+                int statusRes = makeGetRequest(compactUrl, responseData);
+                lastStatus = responseData;
+                // Compaction status returns 200 with "status":"SUCCESS" when complete
+                // or "status":"RUNNING" while in progress
+                if (statusRes == 200 && responseData.find("SUCCESS") != std::string::npos) {
+                    return true;
+                }
+                return false;
+            },
+            1000))
+            << "Compaction did not complete within timeout. Last status: " << lastStatus;
     }
 
     // Create a reader with readCompacted enabled