ob-scheme: Fix :prologue handling

* lisp/ob-scheme.el (org-babel-expand-body:scheme): Handle :prologue
  handling without any :var parameter.
* testing/lisp/test-ob-scheme.el: New file.

lisp/ob-scheme.el

@@ -64,16 +64,16 @@
 (defun org-babel-expand-body:scheme (body params)
   "Expand BODY according to PARAMS, return the expanded body."
   (let ((vars (org-babel--get-vars params))
-	(prepends (cl-remove-if-not (lambda (x) (eq (car x) :prologue)) params)))
-    (if (> (length vars) 0)
-        (concat (mapconcat (lambda (p) (format "%s" (cdr p)))
-			   prepends "\n     ")
-	        "(let ("
-                (mapconcat
-                 (lambda (var) (format "%S" (print `(,(car var) ',(cdr var)))))
-                 vars "\n      ")
-                ")\n" body ")")
-      body)))
+	(prepends (cdr (assq :prologue params))))
+    (concat (and prepends (concat prepends "\n"))
+	    (if (null vars) body
+	      (format "(let (%s)\n%s\n)"
+		      (mapconcat
+		       (lambda (var)
+			 (format "%S" (print `(,(car var) ',(cdr var)))))
+		       vars
+		       "\n      ")
+		      body)))))
 
 
 (defvar org-babel-scheme-repl-map (make-hash-table :test 'equal)

testing/lisp/test-ob-scheme.el

@@ -0,0 +1,70 @@
+;;; test-ob-scheme.el --- Tests for Babel scheme     -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017  Nicolas Goaziou
+
+;; Author: Nicolas Goaziou <mail@nicolasgoaziou.fr>
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Unit tests for Org Babel Scheme.
+
+;;; Code:
+
+(unless (featurep 'ob-scheme)
+  (signal 'missing-test-dependency "Support for Scheme code blocks"))
+
+(ert-deftest test-ob-scheme/tables ()
+  "Test table output."
+  (equal "#+begin_src scheme
+'(1 2 3)
+#+end_src
+
+#+RESULTS:
+| 1 | 2 | 3 |
+"
+	 (org-test-with-temp-text "#+begin_src scheme\n'(1 2 3)\n#+end_src"
+	   (org-babel-execute-maybe)
+	   (buffer-string))))
+
+(ert-deftest test-ob-scheme/prologue ()
+  "Test :prologue parameter."
+  (equal "#+begin_src scheme :prologue \"(define x 2)\"
+x
+#+end_src
+
+#+RESULTS:
+: 2
+"
+	 (org-test-with-temp-text
+	     "#+begin_src scheme :prologue \"(define x 2)\"\nx\n#+end_src"
+	   (org-babel-execute-maybe)
+	   (buffer-string)))
+  (equal
+   "#+begin_src scheme :prologue \"(define x 2)\" :var y=1
+x
+#+end_src
+
+#+RESULTS:
+: 2
+"
+   (org-test-with-temp-text
+       "#+begin_src scheme :prologue \"(define x 2)\" :var y=1\nx\n#+end_src"
+     (org-babel-execute-maybe)
+     (buffer-string))))
+
+
+(provide 'test-ob-scheme)
+;;; test-ob-scheme.el ends here