diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 93bed91ef654d2760a5eabbf30b08e3428c3cc59..3d35b9724dbd7c8d7d4492c7996ec2dca421c44a 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -7,6 +7,9 @@ include:
   - project: shore/ci-templates
     file: templates/gitlab-release.yml
 
+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
 build-wheel:
   extends: .python3-build
   script:
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000000000000000000000000000000000..47741028726c137743c6bee7c69bcd224b01de60
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "tests/bats_helpers/bats-assert"]
+	path = tests/bats_helpers/bats-assert
+	url = https://github.com/bats-core/bats-assert.git
diff --git a/tests/bats_helpers/bats-assert b/tests/bats_helpers/bats-assert
new file mode 160000
index 0000000000000000000000000000000000000000..e0de84e9c011223e7f88b7ccf1c929f4327097ba
--- /dev/null
+++ b/tests/bats_helpers/bats-assert
@@ -0,0 +1 @@
+Subproject commit e0de84e9c011223e7f88b7ccf1c929f4327097ba
diff --git a/tests/mnpw.bats b/tests/mnpw.bats
deleted file mode 100644
index 731e64c3c07122315e264cc91f7865c36126f2bd..0000000000000000000000000000000000000000
--- a/tests/mnpw.bats
+++ /dev/null
@@ -1,49 +0,0 @@
-# vim:ft=bash
-
-@test "help" {
-    run dist/mnpw --help
-    [ "$status" -eq 0 ]
-}
-
-@test "version" {
-    run dist/mnpw --version
-    [ "$status" -eq 0 ]
-}
-
-@test "true" {
-    run dist/mnpw true
-    [ "$status" -eq 0 ]
-}
-
-@test "command not found" {
-    run dist/mnpw --dry-run /foobar
-    [ "$status" -eq 2 ]
-}
-
-@test "warning" {
-    run dist/mnpw --dry-run -- /bin/sh -c 'exit 1'
-}
-
-@test "critical" {
-    run dist/mnpw --dry-run -- /bin/sh -c 'exit 2'
-}
-
-@test "unknown" {
-    run dist/mnpw --dry-run -- /bin/sh -c 'exit 3'
-}
-
-@test "other" {
-    run dist/mnpw --dry-run -- /bin/sh -c 'exit 4'
-}
-
-@test "timeout" {
-    run dist/mnpw --dry-run --timeout 2 -- /bin/sh -c 'sleep 6'
-    [ "$status" -eq 2 ]
-}
-
-@test "quiet" {
-    run dist/mnpw --dry-run --quiet false
-    [ "$output" = '' ]
-    run dist/mnpw --dry-run --quiet foobar
-    [ "$output" != '' ]
-}
diff --git a/tests/test_mnpw.bats b/tests/test_mnpw.bats
new file mode 100644
index 0000000000000000000000000000000000000000..f5c028f6a4742fbfbc0f16a9664a7430a13576e9
--- /dev/null
+++ b/tests/test_mnpw.bats
@@ -0,0 +1,61 @@
+# vim:ft=bash
+
+setup () {
+    load "bats_helpers/bats-assert/load"
+    PATH="$BATS_TEST_DIRNAME/../dist:$PATH"
+}
+
+@test "help" {
+    run mnpw --help
+    assert_success
+    assert_output --partial 'usage:'
+}
+
+@test "version" {
+    run mnpw --version
+    assert_success
+    assert_output --partial 'mnpw version'
+}
+
+@test "silent and verbose" {
+    run mnpw --silent --verbose /bin/true
+    assert_failure 2
+}
+
+@test "true" {
+    run mnpw /bin/true
+    assert_success
+}
+
+@test "command not found" {
+    run mnpw --dry-run /foobar
+    assert_failure 2
+}
+
+@test "warning" {
+    run mnpw --dry-run -- /bin/sh -c 'exit 1'
+}
+
+@test "critical" {
+    run mnpw --dry-run -- /bin/sh -c 'exit 2'
+}
+
+@test "unknown" {
+    run mnpw --dry-run -- /bin/sh -c 'exit 3'
+}
+
+@test "invalid return code" {
+    run mnpw --dry-run -- /bin/sh -c 'exit 4'
+}
+
+@test "timeout" {
+    run mnpw --dry-run --timeout 2 -- /bin/sh -c 'sleep 6'
+    assert_failure 2
+}
+
+@test "quiet" {
+    run mnpw --dry-run --quiet false
+    assert_output ''
+    run mnpw --dry-run --quiet foobar
+    assert_output
+}
diff --git a/tests/test_nagios.py b/tests/test_nagios.py
index 2483c6e3d5c8356c14a4682812e3f7d3287a493c..4a7e1c58e5540cb7a12cc1c960a3996d05588042 100644
--- a/tests/test_nagios.py
+++ b/tests/test_nagios.py
@@ -19,6 +19,20 @@ DISK OK - free space: / 3326 MB (56%); | /=2643MB;5948;5958;0;5968
 /var/log=818MB;970;975;0;980
 """
 
+# Lifted from the Alignak project:
+# https://github.com/Alignak-monitoring/alignak/blob/fcc3d6499478ce67f4b91c694111f45cc8282535/tests/test_perfdata_parsing.py
+PERF_DATA_1 = """ramused=90%;85;95;;"""
+PERF_DATA_2 = """ramused=1009MB;;;0;1982 """
+PERF_DATA_3 = """memused=1550MB;2973;3964;0;5810"""
+PERF_DATA_4 = """swapused=540MB;;;; """
+PERF_DATA_5 = """memused=90%"""
+PERF_DATA_6 = """'Physical Memory Used'=12085620736Bytes; """
+PERF_DATA_7 = """Physical Memory Utilisation'=94%;80;90;"""
+PERF_DATA_8 = """'C: used'=13.06452GB;22.28832;25.2601;0;29.71777 """
+PERF_DATA_9 = """'C: used %'=44%;75;85;0;100"""
+PERF_DATA_10 = """time_offset-192.168.0.1=-7.22636468709e-05s;1;2;0;;"""
+PERF_DATA_11 = """àéèï-192.168.0.1=-7.22636468709e-05s;1;2;0;;"""
+
 
 @pytest.mark.parametrize(
     "command,args,exit_code",