Merge pull request #6526 from metabase/async-test-fix-race-condition

Fix potential race condition where the job gets cleaned up too soon.

test/metabase/test/async.clj

@@ -7,11 +7,13 @@
 (defn result!
   "Blocking version of async/result."
   [job-id]
-  (-> #'async/running-jobs
-      deref          ; var
-      deref          ; atom
-      (get job-id)
-      deref)         ; future
+  (when-let [f (-> #'async/running-jobs
+                   deref                  ; var
+                   deref                  ; atom
+                   (get job-id))]
+    (when-not (or (future-cancelled? f)
+                  (future-done? f))
+      @f))
   (async/result (ComputationJob job-id)))
 
 (def ^:dynamic *max-while-runtime*
@@ -19,7 +21,8 @@
   10000000)
 
 (defmacro while-with-timeout
-  "Like while except it runs a maximum of `*max-while-runtime*` milliseconds."
+  "Like `clojure.core/while` except it runs a maximum of `*max-while-runtime*`
+   milliseconds (assuming running time for one iteration is << `*max-while-runtime*`)."
   [test & body]
   `(let [start# (System/currentTimeMillis)]
      (while (and ~test