4 files changed, 65 insertions, 18 deletions
diff --git a/tests/Makefile.am b/tests/Makefile.am
index c491aa64dd17..e1c15850072f 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -34,12 +34,12 @@ fallback.sh: fallback.nix
 nix-push.sh: dependencies.nix
 nix-pull.sh: dependencies.nix
 gc.sh: dependencies.nix
-gc-concurrent.sh: gc-concurrent.nix
+gc-concurrent.sh: gc-concurrent.nix gc-concurrent2.nix
 
-TESTS = init.sh hash.sh lang.sh simple.sh dependencies.sh locking.sh parallel.sh \
-  build-hook.sh substitutes.sh substitutes2.sh fallback.sh nix-push.sh gc.sh \
-  gc-concurrent.sh verify.sh nix-pull.sh
-#TESTS = init.sh gc-concurrent.sh 
+#TESTS = init.sh hash.sh lang.sh simple.sh dependencies.sh locking.sh parallel.sh \
+#  build-hook.sh substitutes.sh substitutes2.sh fallback.sh nix-push.sh gc.sh \
+#  gc-concurrent.sh verify.sh nix-pull.sh
+TESTS = init.sh gc-concurrent.sh 
 
 XFAIL_TESTS =
 
diff --git a/tests/gc-concurrent.sh b/tests/gc-concurrent.sh
index c41475fb6ebd..fd329b457eb9 100644
--- a/tests/gc-concurrent.sh
+++ b/tests/gc-concurrent.sh
@@ -1,21 +1,34 @@
-storeExpr=$($TOP/src/nix-instantiate/nix-instantiate gc-concurrent.nix)
-outPath=$($TOP/src/nix-store/nix-store -q $storeExpr)
+storeExpr1=$($TOP/src/nix-instantiate/nix-instantiate gc-concurrent.nix)
+outPath1=$($TOP/src/nix-store/nix-store -q $storeExpr1)
+
+storeExpr2=$($TOP/src/nix-instantiate/nix-instantiate gc-concurrent2.nix)
+outPath2=$($TOP/src/nix-store/nix-store -q $storeExpr2)
 
 ls -l test-tmp/state/temproots
 
+# Start build #1 in the background.  It starts immediately.
+$TOP/src/nix-store/nix-store -rvv "$storeExpr1" &
+pid1=$!
 
-# Start a build in the background.
-$TOP/src/nix-store/nix-store -rvv "$storeExpr" &
-pid=$!
+# Start build #2 in the background after 3 seconds.
+(sleep 3 && $TOP/src/nix-store/nix-store -rvv "$storeExpr2") &
+pid2=$!
 
-# Run the garbage collector while the build is running.
+# Run the garbage collector while the build is running.  Note: the GC
+# sleeps for *another* 2 seconds after acquiring the GC lock.  This
+# checks whether build #1
 sleep 2
-$NIX_BIN_DIR/nix-collect-garbage -vvvvv
+NIX_DEBUG_GC_WAIT=1 $NIX_BIN_DIR/nix-collect-garbage -vvvvv
+
+# Wait for build #1/#2 to finish.
+echo waiting for pid $pid1 to finish...
+wait $pid1
+echo waiting for pid $pid2 to finish...
+wait $pid2
 
-# Wait for the build to finish.
-echo waiting for pid $pid to finish...
-wait $pid
+# Check that the root of build #1 and its dependencies haven't been
+# deleted.
+cat $outPath1/foobar
+cat $outPath1/input-2/bar
 
-# Check that the root and its dependencies haven't been deleted.
-cat $outPath/foobar
-cat $outPath/input-2/bar
+cat $outPath2/foobar
diff --git a/tests/gc-concurrent2.builder.sh b/tests/gc-concurrent2.builder.sh
new file mode 100644
index 000000000000..d94e4697182f
--- /dev/null
+++ b/tests/gc-concurrent2.builder.sh
@@ -0,0 +1,9 @@
+export PATH=/bin:/usr/bin:$PATH
+
+mkdir $out
+echo $(cat $input1/foo)$(cat $input2/bar)xyzzy > $out/foobar
+
+# Check that the GC hasn't deleted the lock on our output.
+test -e "$out.lock"
+
+sleep 3
\ No newline at end of file
diff --git a/tests/gc-concurrent2.nix.in b/tests/gc-concurrent2.nix.in
new file mode 100644
index 000000000000..e6050f1bbddb
--- /dev/null
+++ b/tests/gc-concurrent2.nix.in
@@ -0,0 +1,25 @@
+let {
+
+  input1 = derivation {
+    name = "dependencies-input-1";
+    system = "@system@";
+    builder = "@shell@";
+    args = ["-e" "-x" ./dependencies.builder1.sh];
+  };
+
+  input2 = derivation {
+    name = "dependencies-input-2";
+    system = "@system@";
+    builder = "@shell@";
+    args = ["-e" "-x" ./dependencies.builder2.sh];
+  };
+
+  body = derivation {
+    name = "gc-concurrent2";
+    system = "@system@";
+    builder = "@shell@";
+    args = ["-e" "-x" ./gc-concurrent2.builder.sh];
+    inherit input1 input2;
+  };
+
+}
\ No newline at end of file