tests: Skip network-dependent tests when the network is unreachable.

* tests/builders.scm (network-reachable?): New variable.
  ("url-fetch", "gnu-build"): Skip unless NETWORK-REACHABLE?.
* tests/derivations.scm (%coreutils): Check for network access.
  ("build-expression->derivation with one input"): Skip when %COREUTILS
  is #f.
* tests/guix-package.sh: Skip installation of GNU Make when the network
  is unreachable.
* tests/packages.scm ("GNU Make, bootstrap"): Likewise.
* tests/union.scm ("union-build"): Likewise.

tests/builders.scm

@@ -50,9 +50,13 @@
               (list name (package-derivation %store package))))
             (@@ (distro packages base) %boot0-inputs))))
 
+(define network-reachable?
+  (false-if-exception (getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)))
+
 
 (test-begin "builders")
 
+(unless network-reachable? (test-skip 1))
 (test-assert "url-fetch"
   (let* ((url      '("http://ftp.gnu.org/gnu/hello/hello-2.8.tar.gz"
                      "ftp://ftp.gnu.org/gnu/hello/hello-2.8.tar.gz"))
@@ -69,6 +73,7 @@
   (and (build-system? gnu-build-system)
        (eq? gnu-build (build-system-builder gnu-build-system))))
 
+(unless network-reachable? (test-skip 1))
 (test-assert "gnu-build"
   (let* ((url      "http://ftp.gnu.org/gnu/hello/hello-2.8.tar.gz")
          (hash     (nix-base32-string->bytevector

tests/derivations.scm

@@ -290,8 +290,9 @@
 
 (define %coreutils
   (false-if-exception
+   (and (getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)
         (or (package-derivation %store %bootstrap-coreutils&co)
-       (nixpkgs-derivation "coreutils"))))
+            (nixpkgs-derivation "coreutils")))))
 
 (test-skip (if %coreutils 0 1))
 
@@ -385,6 +386,7 @@
            (and (equal? '(hello) (call-with-input-file one read))
                 (equal? '(world) (call-with-input-file two read)))))))
 
+(test-skip (if %coreutils 0 1))
 (test-assert "build-expression->derivation with one input"
   (let* ((builder    '(call-with-output-file %output
                         (lambda (p)

tests/guix-package.sh

@@ -31,6 +31,9 @@ test -L "$profile" && test -L "$profile-1-link"
 test -f "$profile/bin/guile"
 
 
+# Check whether we have network access.
+if guile -c '(getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)' 2> /dev/null
+then
     guix-package -b -p "$profile"						\
 	-i `guix-build -e '(@@ (distro packages base) gnu-make-boot0)'`
     test -L "$profile-2-link"
@@ -56,6 +59,7 @@ test "`guix-package -p "$profile" -I 'g.*e' | cut -f1`" = "guile-bootstrap"
     guix-package -b -p "$profile" -r "guile-bootstrap-2.0"
     test -L "$profile-3-link"
     test -f "$profile/bin/make" && ! test -f "$profile/bin/guile"
+fi
 
 # Make sure the `:' syntax works.
 guix-package -b -i "libsigsegv:lib" -n

tests/packages.scm

@@ -125,6 +125,8 @@
          (let ((p (pk 'drv d (derivation-path->output-path d))))
            (eq? 'hello (call-with-input-file p read))))))
 
+(unless (false-if-exception (getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV))
+  (test-skip 1))
 (test-assert "GNU Make, bootstrap"
   ;; GNU Make is the first program built during bootstrap; we choose it
   ;; here so that the test doesn't last for too long.

tests/union.scm

@@ -64,7 +64,11 @@
                 (bin make)
                 (share (doc (make README))))))
 
-(test-skip (if %store 0 1))
+(test-skip (if (and %store
+                    (false-if-exception
+                     (getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)))
+               0
+               1))
 
 (test-assert "union-build"
   (let* ((inputs  (map (match-lambda