Fixed linting error, added test

.mega-linter.yml

@@ -33,7 +33,6 @@ JSON_REPORTER: true
 GITHUB_STATUS_REPORTER: false
 PLUGINS:
   - https://raw.githubusercontent.com/megalinter/megalinter/main/.automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml
-  - file://.automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml
 PRE_COMMANDS:
   - command: echo "This is MegaLinter PRE_COMMAND on own MegaLinter ! :)"
     cwd: "root"

README.md

@@ -882,43 +882,48 @@ _Note:_ IF you did not use `MegaLinter` as GitHub Action name, please read [GitH
 <!-- badge-section-end -->
 
 <!-- plugins-section-start -->
-## Plugins
+# Plugins
 
 For security reasons, we try to embed in MegaLinter only linters that are widely adopted by open-source community.
 
 But any linter can be callable within MegaLinter thanks to the plugin mechanism !
 
-### Use plugins
+## Use plugins
 
-Just add plugin URLs in `PLUGINS` property of `.mega-linter.yml`
+Add plugin URLs in `PLUGINS` property of `.mega-linter.yml`. URLs must either begin with "https://" or take the form of "file://\<path\>", where \<path\> points to a valid plugin descriptor file.
 
-#### Example
+> Note: Both \<path\> and the default mount directory (/tmp/lint/\<path\>) will be checked for a valid descriptor.
+
+### Example
 
 ```yaml
 PLUGINS:
   - https://raw.githubusercontent.com/megalinter/megalinter/main/.automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml
   - https://raw.githubusercontent.com/cookiejar/mega-linter-plugin-cookietemple/main/cookietemple.megalinter-descriptor.yml
+  - file://.automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml
 ```
 
-### Plugins Catalog
+## Plugins Catalog
 
 * [jupyfmt](https://github.com/kpj/jupyfmt): The uncompromising Jupyter notebook formatter ([usage](https://github.com/kpj/jupyfmt#mega-linter-integration))
 * [nitpick](https://github.com/andreoliwa/nitpick): Command-line tool and flake8 plugin to enforce the same settings across multiple language-independent projects. ([usage](https://github.com/andreoliwa/nitpick#run-as-a-megalinter-plugin))
 
 
 Submit a PR if you want your plugin to appear here :)
 
-### Create plugins
+## Create plugins
 
 You can implement your own descriptors and load them as plugins during MegaLinter runtime
 
-- Plugins descriptor files must be named **\*\*.megalinter-descriptor.yml** and respect [MegaLinter Json Schema](https://github.com/megalinter/megalinter/blob/main/megalinter/descriptors/schemas/megalinter-descriptor.jsonschema.json)
 - Descriptor format is exactly the same than [MegaLinter embedded ones](https://github.com/megalinter/megalinter/tree/main/megalinter/descriptors) ([see json schema documentation](https://megalinter.github.io/json-schemas/descriptor.html))
+- Plugins descriptor files must be named **\*\*.megalinter-descriptor.yml** and respect [MegaLinter Json Schema](https://github.com/megalinter/megalinter/blob/main/megalinter/descriptors/schemas/megalinter-descriptor.jsonschema.json)
 - Plugins must be hosted in a url containing **\*\*/mega-linter-plugin-\*\*/**
+- File URLs must conform to the same directory and file naming criteria as defined above.
 
-#### Limitations
+### Limitations
 
 - For now, the only `install` attributes managed are `dockerfile` instructions starting by `RUN`
+
 <!-- plugins-section-end -->
 
 <!-- articles-section-start -->

megalinter/plugin_factory.py

@@ -1,9 +1,9 @@
 # Class to manage MegaLinter plugins
 import logging
+import os
 import shutil
 import subprocess
 import sys
-import os
 
 import requests
 import yaml
@@ -48,10 +48,14 @@ def load_plugin(plugin):
                 if not os.path.isfile(plugin_path):
                     plugin_path = "/tmp/lint/" + plugin_path
                     if not os.path.isfile(plugin_path):
-                        raise Exception(f"[Plugins] Local plugin descriptor {plugin} not found")
+                        raise Exception(
+                            f"[Plugins] Local plugin descriptor {plugin} not found"
+                        )
                 # Make sure plugin file is readable and not empty
                 if not os.access(plugin_path, os.R_OK):
-                    raise Exception(f"[Plugins] Local plugin descriptor {plugin} not readable")
+                    raise Exception(
+                        f"[Plugins] Local plugin descriptor {plugin} not readable"
+                    )
                 if os.stat(plugin_path).st_size == 0:
                     raise Exception(f"[Plugins] Plugin descriptor {plugin} is empty")
                 r = open(plugin_path, "r").read()
@@ -63,12 +67,15 @@ def load_plugin(plugin):
                 f"[Plugins] Loaded plugin descriptor {descriptor_file} from {plugin}"
             )
         except Exception as e:
-            raise Exception(f"[Plugins] Unable to load remote plugin {plugin}:\n{str(e)}")
+            raise Exception(
+                f"[Plugins] Unable to load remote plugin {plugin}:\n{str(e)}"
+            )
         return descriptor_file
     else:
         raise Exception(
             "[Plugins] Plugin descriptors must follow the format"
-            f" https://**/mega-linter-plugin-**/**.mega-linter-descriptor.yml or file://**/mega-linter-plugin-**/**.mega-linter-descriptor.yml (wrong value {plugin})"
+            " https://**/mega-linter-plugin-**/**.mega-linter-descriptor.yml or"
+            f" file://**/mega-linter-plugin-**/**.mega-linter-descriptor.yml (wrong value {plugin})"
         )
 
 

megalinter/tests/test_megalinter/plugins_test.py

@@ -42,6 +42,22 @@ def test_load_plugin_success(self):
         self.assertIn("[Plugins] Loaded plugin descriptor", output)
         self.assertIn("[Plugins] Successful initialization of TEST", output)
 
+    def test_load_local_plugin_success(self):
+        mega_linter, output = utilstest.call_mega_linter(
+            {
+                "PLUGINS": ".automation/test/mega-linter-plugin-test/test.megalinter-descriptor.yml",
+                "LOG_LEVEL": "DEBUG",
+                "MULTI_STATUS": "false",
+                "GITHUB_COMMENT_REPORTER": "false",
+            }
+        )
+        self.assertTrue(
+            len(mega_linter.linters) > 0, "Linters have been created and run"
+        )
+        self.assertIn("### Processed [TEST] files", output)
+        self.assertIn("[Plugins] Loaded plugin descriptor", output)
+        self.assertIn("[Plugins] Successful initialization of TEST", output)
+
     def test_load_plugin_http_error(self):
         try:
             utilstest.call_mega_linter(