[gobject-introspection] tests: Remove temporary files created when testing transformer

[Christoph Reiter <creiter src gnome org>]

commit 094446e58d8de6724c50e93d4c475d604a5f2551
Author: Tomasz Miąsko <tomasz miasko gmail com>
Date:   Sat Dec 22 00:00:00 2018 +0000

    tests: Remove temporary files created when testing transformer

 tests/scanner/test_transformer.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/tests/scanner/test_transformer.py b/tests/scanner/test_transformer.py
index 27bfad58..4731b5ce 100644
--- a/tests/scanner/test_transformer.py
+++ b/tests/scanner/test_transformer.py
@@ -16,11 +16,14 @@ from giscanner.message import MessageLogger, WARNING, ERROR, FATAL
 def create_scanner_from_source_string(source):
     ss = SourceScanner()
     tmp_fd, tmp_name = tempfile.mkstemp(suffix='.h', text=True)
-    file = os.fdopen(tmp_fd, 'wt')
-    file.write(source)
-    file.close()
 
-    ss.parse_files([tmp_name])
+    try:
+        with os.fdopen(tmp_fd, 'wt') as file:
+            file.write(source)
+        ss.parse_files([tmp_name])
+    finally:
+        os.unlink(tmp_name)
+
     return ss