project tests: Also regen before building

This actually caught a cached-dependency related bug for me that the
test-time regen did not. I also increased the ninja wait time to
1 second because that's actually how long you need to sleep to be
guaranteed that a change will be detected.

Must poke upstream about https://github.com/ninja-build/ninja/issues/371

run_project_tests.py

@@ -36,6 +36,7 @@ import concurrent.futures as conc
 import re
 
 from run_tests import get_backend_commands, get_backend_args_for_dir, Backend
+from run_tests import ensure_backend_detects_changes
 
 
 class BuildStep(Enum):
@@ -342,6 +343,10 @@ def _run_test(testdir, test_build_dir, install_dir, extra_args, compiler, backen
         return TestResult('Test that should have failed succeeded', BuildStep.configure, stdo, stde, mesonlog, gen_time)
     if returncode != 0:
         return TestResult('Generating the build system failed.', BuildStep.configure, stdo, stde, mesonlog, gen_time)
+    # Touch the meson.build file to force a regenerate so we can test that
+    # regeneration works before a build is run.
+    ensure_backend_detects_changes(backend)
+    os.utime(os.path.join(testdir, 'meson.build'))
     # Build with subprocess
     dir_args = get_backend_args_for_dir(backend, test_build_dir)
     build_start = time.time()
@@ -356,9 +361,8 @@ def _run_test(testdir, test_build_dir, install_dir, extra_args, compiler, backen
     if pc.returncode != 0:
         return TestResult('Compiling source code failed.', BuildStep.build, stdo, stde, mesonlog, gen_time, build_time)
     # Touch the meson.build file to force a regenerate so we can test that
-    # regeneration works. We need to sleep for 0.2s because Ninja tracks mtimes
-    # at a low resolution: https://github.com/ninja-build/ninja/issues/371
-    time.sleep(0.2)
+    # regeneration works after a build is complete.
+    ensure_backend_detects_changes(backend)
     os.utime(os.path.join(testdir, 'meson.build'))
     test_start = time.time()
     # Test in-process

run_tests.py

@@ -16,6 +16,7 @@
 
 import os
 import sys
+import time
 import shutil
 import subprocess
 import platform
@@ -98,6 +99,13 @@ def get_backend_commands(backend, debug=False):
         raise AssertionError('Unknown backend: {!r}'.format(backend))
     return cmd, clean_cmd, test_cmd, install_cmd, uninstall_cmd
 
+def ensure_backend_detects_changes(backend):
+    # This is needed to increase the difference between build.ninja's
+    # timestamp and the timestamp of whatever you changed due to a Ninja
+    # bug: https://github.com/ninja-build/ninja/issues/371
+    if backend is Backend.ninja:
+        time.sleep(1)
+
 def get_fake_options(prefix):
     import argparse
     opts = argparse.Namespace()

run_unittests.py

@@ -30,6 +30,7 @@ from mesonbuild.dependencies import PkgConfigDependency, ExternalProgram
 
 from run_tests import exe_suffix, get_fake_options, FakeEnvironment
 from run_tests import get_builddir_target_args, get_backend_commands, Backend
+from run_tests import ensure_backend_detects_changes
 
 
 def get_soname(fname):
@@ -355,13 +356,6 @@ class BasePlatformTests(unittest.TestCase):
             # XCode backend is untested with unit tests, help welcome!
             self.no_rebuild_stdout = 'UNKNOWN BACKEND {!r}'.format(self.backend.name)
 
-    def ensure_backend_detects_changes(self):
-        # This is needed to increase the difference between build.ninja's
-        # timestamp and the timestamp of whatever you changed due to a Ninja
-        # bug: https://github.com/ninja-build/ninja/issues/371
-        if self.backend is Backend.ninja:
-            time.sleep(1)
-
     def _print_meson_log(self):
         log = os.path.join(self.logdir, 'meson-log.txt')
         if not os.path.isfile(log):
@@ -439,14 +433,14 @@ class BasePlatformTests(unittest.TestCase):
 
     def setconf(self, arg, will_build=True):
         if will_build:
-            self.ensure_backend_detects_changes()
+            ensure_backend_detects_changes(self.backend)
         self._run(self.mconf_command + [arg, self.builddir])
 
     def wipe(self):
         shutil.rmtree(self.builddir)
 
     def utime(self, f):
-        self.ensure_backend_detects_changes()
+        ensure_backend_detects_changes(self.backend)
         os.utime(f)
 
     def get_compdb(self):