>From b72da2bbc450303ffa804b840b5cbbb6efd28b2f Mon Sep 17 00:00:00 2001
From: Maxim Cournoyer <address@hidden>
Date: Sun, 17 Nov 2019 06:01:00 +0900
Subject: [PATCH 1/4] gnu: tests: Reduce the time required to run the system
 tests.

When setting the GUIX_DEV_HACKS environment variable, the Guix package used
inside the instrumented VMs recycles the binaries already found in the Guix
checkout of the developer instead of rebuilding Guix from scratch.  This
brings the time required for this component from 20+ minutes down to 2-3
minutes on an X200 machine.

* gnu/packages/package-management.scm (current-guix/pre-built): New procedure.
* etc/system-tests.scm (tests-for-channel-instance): Use it, when
GUIX_DEV_HACKS is defined.
---
 etc/system-tests.scm                |  5 ++-
 gnu/packages/package-management.scm | 66 +++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/etc/system-tests.scm b/etc/system-tests.scm
index 1085deed24..3bf684e584 100644
--- a/etc/system-tests.scm
+++ b/etc/system-tests.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2016, 2018, 2019, 2020 Ludovic Courtès <address@hidden>
+;;; Copyright © 2020 Maxim Cournoyer <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -49,7 +50,9 @@ instance."
   ;;
   ;;   make check-system TESTS=installed-os
   (parameterize ((current-guix-package
-                  (channel-source->package source #:commit commit)))
+                  (if (getenv "GUIX_DEV_HACKS")
+                      (current-guix/pre-built)
+                      (channel-source->package source #:commit commit))))
     (match (getenv "TESTS")
       (#f
        (all-system-tests))
diff --git a/gnu/packages/package-management.scm b/gnu/packages/package-management.scm
index 3fc6fc404a..4a6f37ba11 100644
--- a/gnu/packages/package-management.scm
+++ b/gnu/packages/package-management.scm
@@ -534,6 +534,72 @@ out) and returning a package that uses that as its 'source'."
                                 #:recursive? #t
                                 #:select? (force select?))))))))
 
+(define-public (current-guix/pre-built)
+  "Similar to `current-guix', but with a modified build procedure that
+reuses the existing byte compiled artifacts to save recompilation time."
+
+  (let* ( ;; The `current-source-directory' macro doesn't work from the REPL.
+         ;; For testing, you can replace it with a static string pointing to
+         ;; your Guix checkout directory.
+         (repository-root (delay (canonicalize-path
+                                  (string-append (current-source-directory)
+                                                 "/../.."))))
+         (select? (lambda (file stat)
+                    (match (basename file)
+                      ((or ".git"
+                           "configure" "autom4te.cache"
+                           "config.log" "config.status"
+                           "stamp-1" "stamp-2" "stamp-3" "stamp-4" "stamp-5"
+                           "stamp-h1" "stamp-vti"
+                           "Makefile" "Makefile.in" ".libs"
+                           ".deps" ".dirstamp"
+                           "test-tmp"
+                           ) #f)
+                      (_ #t)))))
+    (package
+      (inherit guix)
+      (version (string-append (package-version guix) "+"))
+      (source (local-file (force repository-root) "guix-current"
+                          #:recursive? #t
+                          #:select? select?))
+      (arguments
+       (substitute-keyword-arguments (package-arguments guix)
+         ((#:phases phases)
+          `(modify-phases ,phases
+             ;; XXX: References to tools such as 'mkdir' and 'install' are
+             ;; captured in Makefile.in when 'autoconf' is run.  It'd be nicer
+             ;; to find those at configuration time.
+             (delete 'copy-bootstrap-guile)
+             (delete 'check)
+             (delete 'disable-failing-tests)
+             (delete 'strip)            ;can't strip .go files anyway
+             (replace 'build
+               (lambda _
+                 ;; Set the write permission bit on some files that need to be
+                 ;; touched.
+                 (chmod "nix" #o777)
+                 (for-each (lambda (f)
+                             (chmod f #o666))
+                           (cons* "guix-daemon"
+                                  (find-files "." ".*\\.(a|o)$")))
+
+                 ;; The following prevent 'make install' from rebuilding the
+                 ;; daemon and the documentation.
+                 (invoke "make" "--touch" "info"
+                         ;; TODO: Currently we must rebuild the daemon as it
+                         ;; was linked against external dependencies that
+                         ;; depend on the provenance of the profile (or
+                         ;; environment) that was used to build it.
+
+                         ;; If we could query the provenance of any profile,
+                         ;; we could make this package inherit from the guix
+                         ;; inferior that was used to provide such
+                         ;; dependencies.  The most reliable way would
+                         ;; probably be to record that provenance at build
+                         ;; time (as a make target).
+                         ;"guix-daemon"
+                         ))))))))))
+

 ;;;
 ;;; Other tools.
-- 
2.26.2