Improve tiered compaction tests (#7643)

Improves the tiered compaction tests:

* Adds a new test that is a simpler version of the ignored
`test_many_updates_for_single_key` test.
* Reduces the amount of data that `test_many_updates_for_single_key`
processes to make it execute more quickly.
* Adds logging support.

pageserver/compaction/tests/tests.rs

@@ -1,5 +1,20 @@
+use once_cell::sync::OnceCell;
 use pageserver_compaction::interface::CompactionLayer;
 use pageserver_compaction::simulator::MockTimeline;
+use utils::logging;
+
+static LOG_HANDLE: OnceCell<()> = OnceCell::new();
+
+pub(crate) fn setup_logging() {
+    LOG_HANDLE.get_or_init(|| {
+        logging::init(
+            logging::LogFormat::Test,
+            logging::TracingErrorLayerEnablement::EnableWithRustLogFilter,
+            logging::Output::Stdout,
+        )
+        .expect("Failed to init test logging")
+    });
+}
 
 /// Test the extreme case that there are so many updates for a single key that
 /// even if we produce an extremely narrow delta layer, spanning just that one
@@ -11,13 +26,14 @@ use pageserver_compaction::simulator::MockTimeline;
 #[ignore]
 #[tokio::test]
 async fn test_many_updates_for_single_key() {
+    setup_logging();
     let mut executor = MockTimeline::new();
-    executor.target_file_size = 10_000_000; // 10 MB
+    executor.target_file_size = 1_000_000; // 1 MB
 
-    // Ingest 100 MB of updates to a single key.
+    // Ingest 10 MB of updates to a single key.
     for _ in 1..1000 {
         executor.ingest_uniform(100, 10, &(0..100_000)).unwrap();
-        executor.ingest_uniform(10_000, 10, &(0..1)).unwrap();
+        executor.ingest_uniform(1000, 10, &(0..1)).unwrap();
         executor.compact().await.unwrap();
     }
 
@@ -33,3 +49,26 @@ async fn test_many_updates_for_single_key() {
         }
     }
 }
+
+#[tokio::test]
+async fn test_simple_updates() {
+    setup_logging();
+    let mut executor = MockTimeline::new();
+    executor.target_file_size = 500_000; // 500 KB
+
+    // Ingest some traffic.
+    for _ in 1..400 {
+        executor.ingest_uniform(100, 500, &(0..100_000)).unwrap();
+    }
+
+    for l in executor.live_layers.iter() {
+        println!("layer {}: {}", l.short_id(), l.file_size());
+    }
+
+    println!("Running compaction...");
+    executor.compact().await.unwrap();
+
+    for l in executor.live_layers.iter() {
+        println!("layer {}: {}", l.short_id(), l.file_size());
+    }
+}