Improve go test output buffer behavior.

- Use compilation-start to get highlighting of compilation or runtime errors.
- Configure output window in popwin and window-purpose (so that it can be closed
  with C-g for example).
- Configurable buffer name.

layers/+lang/go/README.org

@@ -98,6 +98,10 @@ function testing to work.
 the coverage buffer. See [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Choosing-Window.html][=display-buffer=]] for a list of possible functions.
 The default value is =display-buffer-reuse-window=.
 
+Tests are run in a compilation buffer displayed in a popup window that can be
+closed by pressing ~C-g~ from any other window. The variable
+=go-test-buffer-name= can be customized to set the output buffer name.
+
 ** Guru
 
 Go Oracle has been deprecated as of October 1, 2016, it's replacement is =go-guru=.

layers/+lang/go/config.el

@@ -21,3 +21,6 @@
 
 (defvar go-use-gometalinter nil
   "Use gometalinter if the variable has non-nil value.")
+
+(defvar go-test-buffer-name "*go test*"
+  "Name of the buffer for go test output. Default is *go test*.")

layers/+lang/go/packages.el

@@ -23,9 +23,14 @@
         go-mode
         go-guru
         go-rename
+        popwin
         ))
 
 
+(defun go/post-init-popwin ()
+  (push (cons go-test-buffer-name '(:dedicated t :position bottom :stick t :noselect t :height 0.4))
+        popwin:special-display-config))
+
 (defun go/init-company-go ()
   (use-package company-go
     :defer t
@@ -60,8 +65,7 @@
 
       (defun spacemacs/go-run-tests (args)
         (interactive)
-        (save-selected-window
-          (async-shell-command (concat "go test " args))))
+        (compilation-start (concat "go test " args) nil (lambda (n) go-test-buffer-name) nil))
 
       (defun spacemacs/go-run-package-tests ()
         (interactive)