1 files changed, 35 insertions, 1 deletions

diff --git a/crates/ra_hir_def/src/test_db.rs b/crates/ra_hir_def/src/test_db.rs
index 67714c68e..05018f8e4 100644
--- a/crates/ra_hir_def/src/test_db.rs
+++ b/crates/ra_hir_def/src/test_db.rs
@@ -1,4 +1,7 @@
-use std::{panic, sync::Arc};
+use std::{
+    panic,
+    sync::{Arc, Mutex},
+};
 
 use ra_db::{salsa, CrateId, FileId, FileLoader, FileLoaderDelegate};
 use relative_path::RelativePath;
@@ -13,12 +16,20 @@ use relative_path::RelativePath;
 #[derive(Debug, Default)]
 pub struct TestDB {
     runtime: salsa::Runtime<TestDB>,
+    events: Mutex<Option<Vec<salsa::Event<TestDB>>>>,
 }
 
 impl salsa::Database for TestDB {
     fn salsa_runtime(&self) -> &salsa::Runtime<Self> {
         &self.runtime
     }
+
+    fn salsa_event(&self, event: impl Fn() -> salsa::Event<TestDB>) {
+        let mut events = self.events.lock().unwrap();
+        if let Some(events) = &mut *events {
+            events.push(event());
+        }
+    }
 }
 
 impl panic::RefUnwindSafe for TestDB {}
@@ -38,3 +49,26 @@ impl FileLoader for TestDB {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
 }
+
+impl TestDB {
+    pub fn log(&self, f: impl FnOnce()) -> Vec<salsa::Event<TestDB>> {
+        *self.events.lock().unwrap() = Some(Vec::new());
+        f();
+        self.events.lock().unwrap().take().unwrap()
+    }
+
+    pub fn log_executed(&self, f: impl FnOnce()) -> Vec<String> {
+        let events = self.log(f);
+        events
+            .into_iter()
+            .filter_map(|e| match e.kind {
+                // This pretty horrible, but `Debug` is the only way to inspect
+                // QueryDescriptor at the moment.
+                salsa::EventKind::WillExecute { database_key } => {
+                    Some(format!("{:?}", database_key))
+                }
+                _ => None,
+            })
+            .collect()
+    }
+}