waf: use gtest for tests

It was implemented in such a way that gtest is required only if the user wants
to build and run tests. Initially we're considering all tests should be gtests.
We can change that assumption in the future if necessary.

Tools/ardupilotwaf/ardupilotwaf.py

@@ -1,7 +1,8 @@
 #!/usr/bin/env python
 # encoding: utf-8
 
-from waflib import Logs
+from __future__ import print_function
+from waflib import Logs, Utils
 
 SOURCE_EXTS = [
     '*.S',
@@ -133,15 +134,24 @@ def vehicle_stlib(bld, **kw):
     )
 
 def find_tests(bld, use=[]):
+    if not bld.env.HAS_GTEST:
+        return
+
     features = ''
     if bld.cmd == 'check':
         features='test'
 
+    use = Utils.to_list(use)
+    use.append('GTEST')
+
+    includes = [bld.srcnode.abspath() + '/tests/']
+
     for f in bld.path.ant_glob(incl='*.cpp'):
         target = f.change_ext('.' + bld.env.BOARD)
         bld.program(
             features=features,
             target=target,
+            includes=includes,
             source=[f],
             use=use,
         )

tests/AP_gtest.h

@@ -0,0 +1,11 @@
+/*
+ * Utility header for unit tests with gtest.
+ */
+#include <gtest/gtest.h>
+
+#define AP_GTEST_MAIN() \
+int main(int argc, char *argv[]) \
+{ \
+    ::testing::InitGoogleTest(&argc, argv); \
+    return RUN_ALL_TESTS(); \
+}

wscript

@@ -152,6 +152,13 @@ def configure(cfg):
     cfg.load('clang_compilation_database')
     cfg.load('waf_unit_test')
 
+    cfg.env.HAS_GTEST = cfg.check_cxx(
+        lib='gtest',
+        mandatory=False,
+        uselib_store='GTEST',
+        errmsg='not found, unit tests disabled',
+    )
+
     cfg.msg('Setting board to', cfg.options.board)
     cfg.env.BOARD = cfg.options.board
     board = BOARDS[cfg.env.BOARD]
@@ -223,6 +230,8 @@ def build(bld):
         bld.recurse(d)
 
     if bld.cmd == 'check':
+        if not bld.env.HAS_GTEST:
+            bld.fatal('check: gtest library is required')
         bld.add_post_fun(ardupilotwaf.test_summary)
 
 class CheckContext(waflib.Build.BuildContext):