test/system: Track bats libs as submodules & install them better

This will make it easier to work with system tests.

containers#842

.gitignore

@@ -1,3 +1 @@
 src/toolbox
-test/system/libs/bats-assert
-test/system/libs/bats-support

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "test/system/libs/bats-support"]
+	path = test/system/libs/bats-support
+	url = https://github.com/bats-core/bats-support.git
+[submodule "test/system/libs/bats-assert"]
+	path = test/system/libs/bats-assert
+	url = https://github.com/bats-core/bats-assert.git

meson.build

@@ -3,7 +3,7 @@ project(
   'c',
   version: '0.0.99.2',
   license: 'ASL 2.0',
-  meson_version: '>= 0.40.0',
+  meson_version: '>= 0.42.0',
 )
 
 cc = meson.get_compiler('c')
@@ -38,7 +38,25 @@ endif
 
 install_subdir(
   'test',
-  install_dir: join_paths(get_option('datadir'), meson.project_name())
+  install_dir: join_paths(get_option('datadir'), meson.project_name()),
+  exclude_files: [
+    'system/libs/bats-assert/.git',
+    'system/libs/bats-assert/.gitignore',
+    'system/libs/bats-assert/.travis.yml',
+    'system/libs/bats-assert/package.json',
+    'system/libs/bats-support/.git',
+    'system/libs/bats-support/.gitignore',
+    'system/libs/bats-support/.travis.yml',
+    'system/libs/bats-support/package.json'
+    ],
+  exclude_directories: [
+    'system/libs/bats-assert/.git',
+    'system/libs/bats-assert/script',
+    'system/libs/bats-assert/test',
+    'system/libs/bats-support/.git',
+    'system/libs/bats-support/script',
+    'system/libs/bats-support/test'
+  ]
 )
 
 subdir('data')

test/system/README.md

@@ -18,14 +18,9 @@ tests will clear all podman state (delete all containers, images, etc).
 - `toolbox`
 
 These tests use a few standard libraries for `bats` which help with clarity
-and consistency. In order to use it you need to download them to the `libs`
-directory:
-
-```
-# Go to the Toolbox root folder
-$ git clone https://github.com/bats-core/bats-assert test/system/libs/bats-assert
-$ git clone https://github.com/bats-core/bats-support test/system/libs/bats-support
-```
+and consistency. The libraries are [bats-support](https://github.com/bats-core/bats-support)
+and [bats-assert](https://github.com/bats-core/bats-assert). These libraries are
+provided as git submodules in the `libs` directory. Make sure both are present.
 
 ## Convention