[fix] Deduplicate files

If a file is present in multiple places (templates, configuration)
The last definition wins.

eg:

- the configuration overrides the template
- the second template overrides the first

netjsonconfig/backends/base/backend.py

@@ -107,6 +107,15 @@ def _render_files(self):
             output += file_output
         return output
 
+    def _deduplicate_files(self):
+        files = self.config.get('files', [])
+        if not files:
+            return
+        files_dict = OrderedDict()
+        for file in files:
+            files_dict[file['path']] = file
+        self.config['files'] = list(files_dict.values())
+
     def validate(self):
         try:
             Draft4Validator(self.schema, format_checker=draft4_format_checker).validate(self.config)
@@ -125,6 +134,7 @@ def render(self, files=True):
         # convert NetJSON config to intermediate data structure
         if self.intermediate_data is None:
             self.to_intermediate()
+        self._deduplicate_files()
         # support multiple renderers
         renderers = getattr(self, 'renderers', None) or [self.renderer]
         # convert intermediate data structure to native configuration

tests/openwrt/test_backend.py

@@ -408,3 +408,38 @@ def test_value_error(self):
             OpenWrt(templates=[])
         with self.assertRaises(ValueError):
             OpenWrt(context=[])
+
+    def test_override_file(self):
+        o = OpenWrt({
+            "files": [
+                {
+                    "path": "/etc/crontabs/root",
+                    "mode": "0644",
+                    "contents": "*/5 * * * * /command1\n*/5 * * * * /command2"
+                }
+            ]
+        }, templates=[
+            {
+                "files": [
+                    {
+                        "path": "/etc/crontabs/root",
+                        "mode": "0644",
+                        "contents": "*/5 * * * * /command1"
+                    }
+                ]
+            }
+        ])
+        expected = """
+# ---------- files ---------- #
+
+# path: /etc/crontabs/root
+# mode: 0644
+
+*/5 * * * * /command1
+*/5 * * * * /command2
+
+"""
+        self.assertEqual(o.render(), expected)
+        # ensure the additional files are there present in the tar.gz archive
+        tar = tarfile.open(fileobj=o.generate(), mode='r')
+        self.assertEqual(len(tar.getmembers()), 1)