Update documentation for setupAll and teardownAll

Readme.md

@@ -33,14 +33,6 @@ proc someAsyncProc {.async.} =
 
 suite "test async proc":
 
-  setupAll:
-    # invoke await in the suite setup:
-    await someAsyncProc()
-
-  teardownAll:
-    # invoke await in the suite teardown:
-    await someAsyncProc()
-
   setup:
     # invoke await in each test setup:
     await someAsyncProc()
@@ -55,6 +47,17 @@ suite "test async proc":
 
 ```
 
+setupAll and teardownAll
+------------------------
+
+The `setup` and `teardown` code runs before and after every test, just like the
+standard [unittest][1] module. In addition we provide `setupAll` and
+`teardownAll`. The `setupAll` code runs once before all tests in the suite, and
+the `teardownAll` runs once after all tests in the suite. Use these only as a
+last resort when setting up the test environment is very costly. Be careful that
+the tests do not modify the environment that you set up, lest you introduce
+dependencies between tests.
+
 Unittest2
 ---------
 

asynctest/templates.nim

@@ -2,12 +2,12 @@ template suite*(name, body) =
 
   suite name:
 
-    # Runs before all tests in the suite
+    ## Runs before all tests in the suite
     template setupAll(setupAllBody) {.used.} =
       let b = proc {.async.} = setupAllBody
       waitFor b()
 
-    # Runs after all tests in the suite
+    ## Runs after all tests in the suite
     template teardownAll(teardownAllBody) {.used.} =
       template teardownAllIMPL: untyped {.inject.} =
         let a = proc {.async.} = teardownAllBody