meson: Run the Python test script with Python, not bash

The python build option can be used to swap to a different interpreter,
for environments like the Steam Runtime where the python3 executable in
the PATH is extremely old but there is a better interpreter available.

This is treated as non-optional, because Meson is written in Python,
so the situation where there is no Python interpreter at build-time
shouldn't arise.

Signed-off-by: Simon McVittie <smcv@collabora.com>

meson.build

@@ -64,6 +64,12 @@ endif
 
 bash = find_program('bash', required : false)
 
+if get_option('python') == ''
+  python = find_program('python3')
+else
+  python = find_program(get_option('python'))
+endif
+
 libcap_dep = dependency('libcap', required : true)
 
 selinux_dep = dependency(

meson_options.txt

@@ -21,6 +21,11 @@ option(
   type : 'string',
   description : 'Prepend string to bwrap executable name, for use with subprojects',
 )
+option(
+  'python',
+  type : 'string',
+  description : 'Path to Python 3, or empty to use python3',
+)
 option(
   'require_userns',
   type : 'boolean',

tests/meson.build

@@ -46,10 +46,16 @@ foreach pair : test_programs
 endforeach
 
 foreach test_script : test_scripts
+  if test_script.endswith('.py')
+    interpreter = python
+  else
+    interpreter = bash
+  endif
+
   if meson.version().version_compare('>=0.50.0')
     test(
       test_script,
-      bash,
+      interpreter,
       args : [test_script],
       env : test_env,
       protocol : 'tap',
@@ -57,7 +63,7 @@ foreach test_script : test_scripts
   else
     test(
       test_script,
-      bash,
+      interpreter,
       args : [test_script],
       env : test_env,
     )