bats/background-process: Close file descriptor 3

lib/bats/background-process

@@ -5,14 +5,25 @@
 # These functions make it easier to write Bats test cases that validate the
 # behavior of long-running processes such as servers:
 #
-#   @test '$SUITE: my-server should start successfully' {
+#   @test "$SUITE: my-server should start successfully" {
 #     skip_if_missing_background_utilities
 #     run_in_background 'my-server'
 #     wait_for_background_output 'my-server is now ready'
 #     stop_background_run
 #     assert_...
 #   }
 #
+#   @test "$SUITE: my-test-script should start successfully" {
+#     skip_if_missing_background_utilities
+#     run_in_test_script_in_background 'my-test-script' \
+#       'sleep 1' \
+#       'echo "Hello, World!"' \
+#       'sleep 10'
+#     wait_for_background_output 'Hello, World!'
+#     stop_background_run
+#     assert_...
+#   }
+#
 # Call `skip_if_missing_background_utilities` at the beginning of each test case
 # to skip it if the host system lacks any of the process management utilities
 # required by the functions from this file.
@@ -64,7 +75,18 @@ run_in_background() {
   export BATS_BACKGROUND_RUN_OUTPUT
   BATS_BACKGROUND_RUN_OUTPUT="$BATS_TEST_ROOTDIR/background-run-output.txt"
   printf '' >"$BATS_BACKGROUND_RUN_OUTPUT"
-  "$@" >"$BATS_BACKGROUND_RUN_OUTPUT" 2>&1 &
+
+  # Bats duplicates standard output as file descriptor 3 so that output from its
+  # framework functions isn't captured along with any output from the code under
+  # test. If the code under test contains a `sleep` or other blocking operation,
+  # this file descriptor will be held open until the process becomes unblocked,
+  # preventing Bats from exiting. Hence, we explicitly close file descriptor 3.
+  #
+  # Any other code running under Bats that opens a background process should
+  # close this file descriptor as well. See:
+  #   - https://github.com/sstephenson/bats/issues/80
+  #   - https://github.com/mbland/go-script-bash/issues/226
+  "$@" >"$BATS_BACKGROUND_RUN_OUTPUT" 2>&1 3>&- &
   export BATS_BACKGROUND_RUN_PID="$!"
   restore_bats_shell_options
 }

tests/bats-background-process.bats

@@ -163,3 +163,27 @@ kill_background_test_script() {
   stop_background_run 'HUP'
   assert_status "$((128 + $(kill -l HUP)))"
 }
+
+@test "$SUITE: bash -c command passes under run_in_background" {
+  skip_if_missing_background_utilities
+  mkdir "$BATS_TEST_ROOTDIR"
+
+  run_in_background bash -c 'echo "Oh hai, Mark."; sleep 60'
+  run wait_for_background_output 'Oh hai, Mark.' '0.25'
+  assert_success
+}
+
+@test "$SUITE: bash -c command fails under run_in_background without hanging" {
+  skip_if_missing_background_utilities
+  mkdir "$BATS_TEST_ROOTDIR"
+
+  run_in_background bash -c 'echo "Oh hai, Mark."; sleep 60'
+  run wait_for_background_output 'I did not do it! I did not!' '0.25'
+  assert_failure \
+    'Output did not match regular expression:' \
+    "  'I did not do it! I did not!'" \
+    '' \
+    'OUTPUT:' \
+    '------' \
+    'Oh hai, Mark.'
+}