Get more tests to pass on Windows

test/handler/test_idris_handler.vader

@@ -1,6 +1,16 @@
 Before:
+  Save $TMPDIR
+
+  " Set TMPDIR so the temporary file checks work.
+  let $TMPDIR = '/tmp'
+
   runtime ale_linters/idris/idris.vim
 
+After:
+  Restore
+
+  call ale#linter#Reset()
+
 Execute(The idris handler should parse messages that reference a single column):
   call ale#test#SetFilename('/tmp/foo.idr')