gnu: gtk+: Enable tests.

* gnu/packages/gtk.scm (gtk+) [arguments]<#:phases>['pre-configure]: Remove phase.
['disable-failing-tests]: New phase.
['pre-check]: New phase.

Signed-off-by: Léo Le Bouter <lle-bout@zaclys.net>

gnu/packages/gtk.scm

@@ -923,10 +923,12 @@ (define-public gtk+-2
     (home-page "https://www.gtk.org/")))
 
 (define-public gtk+
-  (package (inherit gtk+-2)
+  (package
+    (inherit gtk+-2)
     (name "gtk+")
     (version "3.24.24")
-   (source (origin
+    (source
+     (origin
        (method url-fetch)
        (uri (string-append "mirror://gnome/sources/" name "/"
                            (version-major+minor version)  "/"
@@ -989,17 +991,35 @@ (define-public gtk+
                                "--enable-x11-backend"
                                ;; This enables the HTML5 websocket backend.
                                "--enable-broadway-backend")
-      #:phases (modify-phases %standard-phases
-        (add-before 'configure 'pre-configure
+       #:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'disable-failing-tests
            (lambda _
-            ;; Disable most tests, failing in the chroot with the message:
-            ;; D-Bus library appears to be incorrectly set up; failed to read
-            ;; machine uuid: Failed to open "/etc/machine-id": No such file or
-            ;; directory.
-            ;; See the manual page for dbus-uuidgen to correct this issue.
-            (substitute* "testsuite/Makefile.in"
-              (("SUBDIRS = gdk gtk a11y css reftests")
-               "SUBDIRS = gdk"))
+             (substitute* "testsuite/gtk/Makefile.in"
+               (("builderparser cellarea check-icon-names check-cursor-names")
+                "builderparser cellarea check-cursor-names")
+               (("notify no-gtk-init object objects-finalize papersize rbtree")
+                "no-gtk-init papersize rbtree")
+               (("stylecontext templates textbuffer textiter treemodel treepath")
+                "stylecontext textbuffer textiter treemodel treepath"))
+             (substitute* "testsuite/a11y/Makefile.in"
+               (("accessibility-dump tree-performance text children derive")
+                "tree-performance text children derive"))
+             (substitute* "testsuite/reftests/Makefile.in"
+               (("TEST_PROGS = gtk-reftest")
+                "TEST_PROGS = "))
+             #t))
+         (add-before 'check 'pre-check
+           (lambda _
+             ;; Tests require a running X server.
+             (system "Xvfb :1 +extension GLX &")
+             (setenv "DISPLAY" ":1")
+             ;; Tests write to $HOME.
+             (setenv "HOME" (getcwd))
+             ;; Tests look for $XDG_RUNTIME_DIR.
+             (setenv "XDG_RUNTIME_DIR" (getcwd))
+             ;; For missing '/etc/machine-id'.
+             (setenv "DBUS_FATAL_WARNINGS" "0")
              #t))
          (add-after 'install 'move-desktop-files
            ;; Move desktop files into 'bin' to avoid cycle references.