tests: Export 'run-basic-test'.

* gnu/tests/base.scm (run-basic-test): New procedure, extracted from ...
(%test-basic-os): ... here.  Use it.

gnu/tests/base.scm

@@ -30,7 +30,8 @@
   #:use-module (guix monads)
   #:use-module (guix packages)
   #:use-module (srfi srfi-1)
-  #:export (%test-basic-os))
+  #:export (run-basic-test
+            %test-basic-os))
 
 (define %simple-os
   (operating-system
@@ -56,15 +57,10 @@
                  %base-user-accounts))))
 
 
-(define %test-basic-os
-  ;; Monadic derivation that instruments %SIMPLE-OS, runs it in a VM, and runs
-  ;; a series of basic functionality tests.
-  (mlet* %store-monad ((os -> (marionette-operating-system
-                               %simple-os
-                               #:imported-modules '((gnu services herd)
-                                                    (guix combinators))))
-                       (run   (system-qemu-image/shared-store-script
-                               os #:graphic? #f)))
+(define* (run-basic-test os command #:optional (name "basic"))
+  "Return a derivation called NAME that tests basic features of the OS started
+using COMMAND, a gexp that evaluates to a list of strings.  Compare some
+properties of running system to what's declared in OS, an <operating-system>."
   (define test
     #~(begin
         (use-modules (gnu build marionette)
@@ -74,7 +70,7 @@
                      (ice-9 match))
 
         (define marionette
-            (make-marionette (list #$run)))
+          (make-marionette #$command))
 
         (mkdir #$output)
         (chdir #$output)
@@ -160,5 +156,16 @@ info --version")
         (test-end)
         (exit (= (test-runner-fail-count (test-runner-current)) 0))))
 
-    (gexp->derivation "basic" test
-                      #:modules '((gnu build marionette)))))
+  (gexp->derivation name test
+                    #:modules '((gnu build marionette))))
+
+(define %test-basic-os
+  ;; Monadic derivation that instruments %SIMPLE-OS, runs it in a VM, and runs
+  ;; a series of basic functionality tests.
+  (mlet* %store-monad ((os -> (marionette-operating-system
+                               %simple-os
+                               #:imported-modules '((gnu services herd)
+                                                    (guix combinators))))
+                       (run   (system-qemu-image/shared-store-script
+                               os #:graphic? #f)))
+    (run-basic-test os #~(list #$run))))