bug#24937: [PATCH 1/2] tests: Factorize 'file=?'.

["Ludovic Courtès" <ludo@gnu.org>]

* guix/tests.scm (file=?): Add optional 'stat' parameter.  Add fast
patch comparing inode numbers.
* tests/gexp.scm ("imported-files with file-like objects"): Remove
'file=?' procedure and use the one from (guix tests).
---
 guix/tests.scm | 30 +++++++++++++++++-------------
 tests/gexp.scm | 11 +++--------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/guix/tests.scm b/guix/tests.scm
index fc3d521163..e1c194340c 100644
--- a/guix/tests.scm
+++ b/guix/tests.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013-2021 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -182,18 +182,22 @@ (define (random-bytevector n)
             (loop (1+ i)))
           bv))))
 
-(define (file=? a b)
-  "Return true if files A and B have the same type and same content."
-  (and (eq? (stat:type (lstat a)) (stat:type (lstat b)))
-       (case (stat:type (lstat a))
-         ((regular)
-          (equal?
-           (call-with-input-file a get-bytevector-all)
-           (call-with-input-file b get-bytevector-all)))
-         ((symlink)
-          (string=? (readlink a) (readlink b)))
-         (else
-          (error "what?" (lstat a))))))
+(define* (file=? a b #:optional (stat lstat))
+  "Return true if files A and B have the same type and same content.  Call
+STAT to obtain file metadata."
+  (let ((sta (stat a)) (stb (stat b)))
+    (and (eq? (stat:type sta) (stat:type stb))
+         (case (stat:type sta)
+           ((regular)
+            (or (and (= (stat:ino sta) (stat:ino stb))
+                     (= (stat:dev sta) (stat:dev stb)))
+                (equal?
+                 (call-with-input-file a get-bytevector-all)
+                 (call-with-input-file b get-bytevector-all))))
+           ((symlink)
+            (string=? (readlink a) (readlink b)))
+           (else
+            (error "what?" (stat a)))))))
 
 (define (canonical-file? file)
   "Return #t if FILE is in the store, is read-only, and its mtime is 1."
diff --git a/tests/gexp.scm b/tests/gexp.scm
index 39a47d4e8c..0758a49f5f 100644
--- a/tests/gexp.scm
+++ b/tests/gexp.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014-2021 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -827,19 +827,14 @@ (define (canonical-file? file)
                        (files -> `(("a/b/c" . ,q-scm)
                                    ("p/q"   . ,plain)))
                        (drv      (imported-files files)))
-    (define (file=? file1 file2)
-      ;; Assume deduplication is in place.
-      (= (stat:ino (stat file1))
-         (stat:ino (stat file2))))
-
     (mbegin %store-monad
       (built-derivations (list (pk 'drv drv)))
       (mlet %store-monad ((dir -> (derivation->output-path drv))
                           (plain* (text-file "foo" "bar!"))
                           (q-scm* (interned-file q-scm "c")))
         (return
-         (and (file=? (string-append dir "/a/b/c") q-scm*)
-              (file=? (string-append dir "/p/q") plain*)))))))
+         (and (file=? (string-append dir "/a/b/c") q-scm* stat)
+              (file=? (string-append dir "/p/q") plain* stat)))))))
 
 (test-equal "gexp-modules & ungexp"
   '((bar) (foo))
-- 
2.33.0