guix build: Add '--without-tests'.

* guix/scripts/build.scm (transform-package-tests): New procedure.
(%transformations, %transformation-options)
show-transformation-options-help): Add it.
* tests/scripts-build.scm ("options->transformation, without-tests"):
New test.
* doc/guix.texi (Package Transformation Options): Document it.

doc/guix.texi

@@ -9271,6 +9271,28 @@ guix build --with-branch=guile-sqlite3=master cuirass
 This is similar to @option{--with-branch}, except that it builds from
 @var{commit} rather than the tip of a branch.  @var{commit} must be a valid
 Git commit SHA1 identifier or a tag.
+
+@cindex test suite, skipping
+@item --without-tests=@var{package}
+Build @var{package} without running its tests.  This can be useful in
+situations where you want to skip the lengthy test suite of a
+intermediate package, or if a package's test suite fails in a
+non-deterministic fashion.  It should be used with care because running
+the test suite is a good way to ensure a package is working as intended.
+
+Turning off tests leads to a different store item.  Consequently, when
+using this option, anything that depends on @var{package} must be
+rebuilt, as in this example:
+
+@example
+guix install --without-tests=python python-notebook
+@end example
+
+The command above installs @code{python-notebook} on top of
+@code{python} built without running its test suite.  To do so, it also
+rebuilds everything that depends on @code{python}, including
+@code{python-notebook} itself.
+
 @end table
 
 @node Additional Build Options

guix/scripts/build.scm

@@ -393,6 +393,25 @@ a checkout of the Git repository at the given URL."
         (rewrite obj)
         obj)))
 
+(define (transform-package-tests specs)
+  "Return a procedure that, when passed a package, sets #:tests? #f in its
+'arguments' field."
+  (define (package-without-tests p)
+    (package/inherit p
+      (arguments
+       (substitute-keyword-arguments (package-arguments p)
+         ((#:tests? _ #f) #f)))))
+
+  (define rewrite
+    (package-input-rewriting/spec (map (lambda (spec)
+                                         (cons spec package-without-tests))
+                                       specs)))
+
+  (lambda (store obj)
+    (if (package? obj)
+        (rewrite obj)
+        obj)))
+
 (define %transformations
   ;; Transformations that can be applied to things to build.  The car is the
   ;; key used in the option alist, and the cdr is the transformation
@@ -403,7 +422,8 @@ a checkout of the Git repository at the given URL."
     (with-graft  . ,transform-package-inputs/graft)
     (with-branch . ,transform-package-source-branch)
     (with-commit . ,transform-package-source-commit)
-    (with-git-url . ,transform-package-source-git-url)))
+    (with-git-url . ,transform-package-source-git-url)
+    (without-tests . ,transform-package-tests)))
 
 (define %transformation-options
   ;; The command-line interface to the above transformations.
@@ -423,7 +443,9 @@ a checkout of the Git repository at the given URL."
           (option '("with-commit") #t #f
                   (parser 'with-commit))
           (option '("with-git-url") #t #f
-                  (parser 'with-git-url)))))
+                  (parser 'with-git-url))
+          (option '("without-tests") #t #f
+                  (parser 'without-tests)))))
 
 (define (show-transformation-options-help)
   (display (G_ "
@@ -443,7 +465,10 @@ a checkout of the Git repository at the given URL."
                          build PACKAGE from COMMIT"))
   (display (G_ "
       --with-git-url=PACKAGE=URL
-                         build PACKAGE from the repository at URL")))
+                         build PACKAGE from the repository at URL"))
+  (display (G_ "
+      --without-tests=PACKAGE
+                         build PACKAGE without running its tests")))
 
 
 (define (options->transformation opts)

tests/scripts-build.scm

@@ -264,5 +264,19 @@
                        ((("x" dep3))
                         (map package-source (list dep1 dep3))))))))))))
 
+(test-assert "options->transformation, without-tests"
+  (let* ((dep (dummy-package "dep"))
+         (p   (dummy-package "foo"
+                (inputs `(("dep" ,dep)))))
+         (t   (options->transformation '((without-tests . "dep")
+                                         (without-tests . "tar")))))
+    (with-store store
+      (let ((new (t store p)))
+        (match (bag-direct-inputs (package->bag new))
+          ((("dep" dep) ("tar" tar) _ ...)
+           ;; TODO: Check whether TAR has #:tests? #f when transformations
+           ;; apply to implicit inputs.
+           (equal? (package-arguments dep)
+                   '(#:tests? #f))))))))
 
 (test-end)