Move VS C++17 test to a unit test since it requires env setup.

run_unittests.py

@@ -3097,6 +3097,19 @@ class WindowsTests(BasePlatformTests):
             self.utime(os.path.join(testdir, 'res', 'resource.h'))
             self.assertRebuiltTarget('prog_1')
 
+    @unittest.skipIf(shutil.which('cl') is None, 'Test only applies to VS')
+    def test_msvc_cpp17(self):
+        testdir = os.path.join(self.unit_test_dir, '45 vscpp17')
+        try:
+            self.init(testdir)
+        except subprocess.CalledProcessError:
+            # According to Python docs, output is only stored when
+            # using check_output. We don't use it, so we can't check
+            # that the output is correct (i.e. that it failed due
+            # to the right reason).
+            return
+        self.build()
+
 class DarwinTests(BasePlatformTests):
     '''
     Tests that should run on macOS

test cases/unit/45 vscpp17/meson.build

@@ -0,0 +1,4 @@
+project('msvc_cpp17', 'cpp', default_options: ['cpp_std=c++17'])
+
+exe = executable('msvc_cpp17', 'main.cpp')
+test('msvc_cpp17', exe)

test cases/windows/17 cpp17/meson.build

@@ -1,9 +0,0 @@
-project('msvc_cpp17', 'cpp', default_options: ['cpp_std=c++17'])
-
-compiler = meson.get_compiler('cpp')
-if compiler.get_id() != 'msvc' or compiler.version().version_compare('<19.11')
-    error('MESON_SKIP_TEST Visual Studio 2017 (version 15.3) or later is required for C++17 support')
-endif
-
-exe = executable('msvc_cpp17', 'main.cpp')
-test('msvc_cpp17', exe)