Use release buildtype in Cython tests, and skip unless ninja backend

This matches the tests for Python extensions.

Also include some other cleanups to these `meson.build` files:

Adding `python_dep` is no longer needed, this is automatic now.
Use a single line for `import('python').find_installation()`,
because the result of `import('python')` by itself is not used
for anything.

test cases/cython/1 basic/meson.build

@@ -1,11 +1,14 @@
 project(
   'basic cython project',
   ['cython', 'c'],
-  default_options : ['warning_level=3']
+  default_options : ['warning_level=3', 'buildtype=release'],
 )
 
-py_mod = import('python')
-py3 = py_mod.find_installation()
+if meson.backend() != 'ninja'
+  error('MESON_SKIP_TEST: Ninja backend required')
+endif
+
+py3 = import('python').find_installation()
 py3_dep = py3.dependency(required : false)
 if not py3_dep.found()
   error('MESON_SKIP_TEST: Python library not found.')

test cases/cython/2 generated sources/meson.build

@@ -1,12 +1,16 @@
 project(
   'generated cython sources',
   ['cython'],
+  default_options : ['buildtype=release'],
 )
 
-py_mod = import('python')
-py3 = py_mod.find_installation('python3')
-py3_dep = py3.dependency(required : false)
+if meson.backend() != 'ninja'
+  error('MESON_SKIP_TEST: Ninja backend required')
+endif
+
 fs = import('fs')
+py3 = import('python').find_installation('python3')
+py3_dep = py3.dependency(required : false)
 if not py3_dep.found()
   error('MESON_SKIP_TEST: Python library not found.')
 endif
@@ -18,7 +22,7 @@ ct = custom_target(
   command : [py3, '@INPUT@', '@OUTPUT@'],
 )
 
-ct_ext = py3.extension_module('ct', ct, dependencies : py3_dep)
+ct_ext = py3.extension_module('ct', ct)
 
 test(
   'custom target',
@@ -35,7 +39,7 @@ cti = custom_target(
   command : [py3, '@INPUT@', '@OUTPUT@'],
 )
 
-cti_ext = py3.extension_module('cti', cti[0], dependencies : py3_dep)
+cti_ext = py3.extension_module('cti', cti[0])
 
 cf = configure_file(
   input : 'configure.pyx.in',
@@ -43,7 +47,7 @@ cf = configure_file(
   copy : true,
 )
 
-cf_ext = py3.extension_module('cf', cf, dependencies : py3_dep)
+cf_ext = py3.extension_module('cf', cf)
 
 test(
   'configure file',
@@ -61,7 +65,6 @@ gen = generator(
 g_ext = py3.extension_module(
   'g',
   gen.process('g.in'),
-  dependencies : py3_dep,
 )
 
 test(

test cases/cython/3 cython_args/meson.build

@@ -1,7 +1,14 @@
-project('cython_args', ['cython', 'c'])
+project('cython_args', ['cython', 'c'],
+  # Needed because Windows Python builds are release-only and tend to be
+  # unhappy with a debug build type.
+  default_options : ['buildtype=release']
+)
 
-pymod = import('python')
-python = pymod.find_installation('python3')
+if meson.backend() != 'ninja'
+  error('MESON_SKIP_TEST: Ninja backend required')
+endif
+
+python = import('python').find_installation('python3')
 python_dep = python.dependency()
 if not python_dep.found()
   error('MESON_SKIP_TEST: Python library not found.')
@@ -12,9 +19,9 @@ mod = python.extension_module(
   files('cythonargs.pyx'),
   cython_args: [
     '--compile-time-env',
-    'VALUE=1'
+    'VALUE=1',
+    '-3',
   ],
-  dependencies: [python_dep]
 )
 
 test(

test cases/python/3 cython/libdir/meson.build

@@ -1,11 +1,11 @@
 pyx_c = custom_target('storer_pyx',
   output : 'storer_pyx.c',
   input : 'storer.pyx',
-  command : [cython, '@INPUT@', '-o', '@OUTPUT@'],
+  command : [cython, '@INPUT@', '-o', '@OUTPUT@', '-3'],
 )
 
 slib = py3.extension_module('storer',
   'storer.c', pyx_c,
-  dependencies : py3_dep)
+)
 
 pydir = meson.current_build_dir()

test cases/python/3 cython/meson.build

@@ -1,6 +1,6 @@
 project('cython', 'c',
-  default_options : ['warning_level=3'])
-
+  default_options : ['warning_level=3', 'buildtype=release']
+)
 if meson.backend() != 'ninja'
   error('MESON_SKIP_TEST: Ninja backend required')
 endif
@@ -10,8 +10,7 @@ if not cython.found()
   error('MESON_SKIP_TEST: Cython3 not found.')
 endif
 
-py_mod = import('python')
-py3 = py_mod.find_installation()
+py3 = import('python').find_installation(pure: false)
 py3_dep = py3.dependency(required: false)
 if not py3_dep.found()
   error('MESON_SKIP_TEST: Python library not found.')