unittests: convert python tests to project tests

Perhaps when this test case was originally created, project tests could
not use a matrix of options? This is certainly possible today, so don't
write special unittest handling for this instead.

This adds proper visibility into what gets run and what doesn't. Now we
know which python executables got tested and which got skipped.

test cases/python/8 different python versions/test.json

@@ -0,0 +1,13 @@
+{
+  "matrix": {
+    "options": {
+      "python": [
+        { "val": null },
+        { "val": "python2" },
+        { "val": "python3" },
+        { "val": "pypy" },
+        { "val": "pypy3" }
+      ]
+    }
+  }
+}

unittests/pythontests.py

@@ -26,48 +26,11 @@ class PythonTests(BasePlatformTests):
     Tests that verify compilation of python extension modules
     '''
 
-    def test_versions(self):
+    def test_bad_versions(self):
         if self.backend is not Backend.ninja:
             raise unittest.SkipTest(f'Skipping python tests with {self.backend.name} backend')
 
-        testdir = os.path.join(self.src_root, 'test cases', 'unit', '39 python extmodule')
-
-        # No python version specified, this will use meson's python
-        self.init(testdir)
-        self.build()
-        self.run_tests()
-        self.wipe()
-
-        # When specifying a known name, (python2 / python3) the module
-        # will also try 'python' as a fallback and use it if the major
-        # version matches
-        try:
-            self.init(testdir, extra_args=['-Dpython=python2'])
-            self.build()
-            self.run_tests()
-        except unittest.SkipTest:
-            # python2 is not necessarily installed on the test machine,
-            # if it is not, or the python headers can't be found, the test
-            # will raise MESON_SKIP_TEST, we could check beforehand what version
-            # of python is available, but it's a bit of a chicken and egg situation,
-            # as that is the job of the module, so we just ask for forgiveness rather
-            # than permission.
-            pass
-
-        self.wipe()
-
-        for py in ('pypy', 'pypy3'):
-            try:
-                self.init(testdir, extra_args=['-Dpython=%s' % py])
-            except unittest.SkipTest:
-                # Same as above, pypy2 and pypy3 are not expected to be present
-                # on the test system, the test project only raises in these cases
-                continue
-
-            # We have a pypy, this is expected to work
-            self.build()
-            self.run_tests()
-            self.wipe()
+        testdir = os.path.join(self.src_root, 'test cases', 'python', '8 different python versions')
 
         # The test is configured to error out with MESON_SKIP_TEST
         # in case it could not find python