add missing test message to message-history

Author: JeanMertz

autoload/rust.vim

@@ -526,7 +526,7 @@ function! rust#Test(all, options) abort
         let func_name = s:SearchTestFunctionNameUnderCursor()
         if func_name ==# ''
             echohl ErrorMsg
-            echo 'No test function was found under the cursor. Please add ! to command if you want to run all tests'
+            echomsg 'No test function was found under the cursor. Please add ! to command if you want to run all tests'
             echohl None
             return
         endif