test: Add a simpler way to run an individual test in integration mode

Aim to treat the scripts in the docker directory as machinery that
doesn't need to be unnecessarily exposed to contributors.

test/README.md

@@ -54,13 +54,14 @@ For details, see
 [test/t/mocks/](https://github.com/CyberShadow/aconfmgr/tree/master/test/t/mocks),
 which contain the implementation for mocked commands.
 
+
 Integration mode
 ----------------
 
 In the "integration" mode, the test suite is executed inside a Docker container containing a minimal installation of Arch Linux.
 The test suite will create the container during execution.
 
-To run a single test in integration mode, run `../docker/run-test.sh ./t-test_file_name_here.sh`.
+To run a single test in integration mode, run `./t-test_file_name_here.sh -i`.
 The Docker service needs to be running and accessible by the current user.
 
 For details, see the [test/docker](https://github.com/CyberShadow/aconfmgr/tree/master/test/docker) directory.

test/t/lib.bash

@@ -9,6 +9,25 @@
 
 source ./lib-init.bash
 
+for arg in "$@"
+do
+	if [[ "$arg" == -i ]]
+	then
+		if ((${ACONFMGR_INTEGRATION:-0}))
+		then
+			printf 'Already in integration mode!\n' 1>&2
+			exit 1
+		else
+			printf 'Re-executing in integration mode.\n' 1>&2
+			exec ../docker/run-test.sh "$ACONFMGR_CURRENT_TEST".sh
+		fi
+	else
+		printf 'Unknown command line switch: %q\n' "$arg" 1>&2
+		exit 1
+	fi
+done
+unset arg
+
 source ../../src/common.bash
 source ../../src/save.bash
 source ../../src/apply.bash