tests: Read environment file if it exists.

tests/__init__.py

@@ -0,0 +1,16 @@
+import os
+
+
+def setup_module():
+    try:
+        with open('build/test-environment') as env_file:
+            for line in env_file:
+                if line.startswith('export '):
+                    line = line[7:]
+                name, sep, value = line.strip().partition('=')
+                if value:
+                    os.environ[name] = value
+                else:
+                    os.environ.pop(name, None)
+    except IOError:
+        pass