Work on adding GTest support.

dependencies.py

@@ -97,4 +97,29 @@ class BoostDependency():
                 flags.append(linkcmd)
         return flags
 
-packages = {'boost': BoostDependency}
+    def get_sources(self):
+        return []
+
+class GTestDependency():
+    def __init__(self, kwargs):
+        self.include_dir = '/usr/include'
+        self.src_include_dir = '/usr/src/gtest'
+        self.src_dir = '/usr/src/gtest/src'
+        self.all_src = os.path.join(self.src_dir, 'gtest-all.cc')
+        self.main_src = os.path.join(self.src_dir, 'gtest_main.cc')
+
+    def found(self):
+        return os.path.exists(self.all_src)
+    def get_compile_flags(self):
+        return ['-I' + self.include_dir, '-I' + self.src_include_dir]
+    def get_link_flags(self):
+        return []
+    def get_version(self):
+        return '1.something_maybe'
+
+    def get_sources(self):
+        return [self.all_src, self.main_src]
+
+packages = {'boost': BoostDependency,
+            'gtest': GTestDependency,
+            }

environment.py

@@ -462,6 +462,11 @@ class Dependency():
     def found(self):
         return False
 
+    def get_sources(self):
+        """Source files that need to be added to the target.
+        As an example, gtest-all.cc when using GTest."""
+        return []
+
 class PackageDependency(Dependency): # Custom detector, not pkg-config.
     def __init__(self, dep):
         Dependency.__init__(self)
@@ -476,6 +481,9 @@ class PackageDependency(Dependency): # Custom detector, not pkg-config.
     def found(self):
         return self.dep.found()
 
+    def get_sources(self):
+        return self.dep.get_sources()
+
 # This should be an InterpreterObject. Fix it.
 
 class PkgConfigDependency(Dependency):

interpreter.py

@@ -381,6 +381,8 @@ class BuildTarget(InterpreterObject):
                not isinstance(dep, ExternalLibraryHolder):
                 raise InvalidArguments('Argument is not an external dependency')
             self.external_deps.append(dep)
+            if isinstance(dep, environment.Dependency):
+                self.process_sourcelist(dep.get_sources())
 
     def get_external_deps(self):
         return self.external_deps
@@ -605,6 +607,8 @@ class Interpreter():
             actual = args[i]
             if wanted != None:
                 if not isinstance(actual, wanted):
+                    print(actual)
+                    print(wanted)
                     raise InvalidArguments('Incorrect argument type.')
 
     def func_project(self, node, args, kwargs):