MDL-62285 privacy: use context id when generating context path

moodle_content_writer::get_context_path() now includes the context
id in the path to ensure that it will always generate unique paths
even when the context names are not unique.

privacy/classes/local/request/moodle_content_writer.php

@@ -244,7 +244,9 @@ protected function get_context_path() : Array {
         $path = [];
         $contexts = array_reverse($this->context->get_parent_contexts(true));
         foreach ($contexts as $context) {
-            $path[] = clean_param($context->get_context_name(), PARAM_FILE);
+            $name = $context->get_context_name();
+            $id = $context->id;
+            $path[] = clean_param("{$name} {$id}", PARAM_FILE);
         }
 
         return $path;

privacy/tests/moodle_content_writer_test.php

@@ -677,6 +677,62 @@ public function test_export_user_preference_context_block($component, $key, $val
         $this->assertEquals($desc, $data->description);
     }
 
+    /**
+     * Writing user preferences for two different blocks with the same name and
+     * same parent context should generate two different context paths and export
+     * files.
+     */
+    public function test_export_user_preference_context_block_multiple_instances() {
+        $this->resetAfterTest();
+
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course();
+        $coursecontext = context_course::instance($course->id);
+        $block1 = $generator->create_block('online_users', ['parentcontextid' => $coursecontext->id]);
+        $block2 = $generator->create_block('online_users', ['parentcontextid' => $coursecontext->id]);
+        $block1context = context_block::instance($block1->id);
+        $block2context = context_block::instance($block2->id);
+        $component = 'block';
+        $desc = 'test preference';
+        $block1key = 'block1key';
+        $block1value = 'block1value';
+        $block2key = 'block2key';
+        $block2value = 'block2value';
+        $writer = $this->get_writer_instance();
+
+        // Confirm that we have two different block contexts with the same name
+        // and the same parent context id.
+        $this->assertNotEquals($block1context->id, $block2context->id);
+        $this->assertEquals($block1context->get_context_name(), $block2context->get_context_name());
+        $this->assertEquals($block1context->get_parent_context()->id, $block2context->get_parent_context()->id);
+
+        $retrieveexport = function($context) use ($writer, $component) {
+            $fileroot = $this->fetch_exported_content($writer);
+
+            $contextpath = $this->get_context_path($context, [get_string('userpreferences')], "{$component}.json");
+            $this->assertTrue($fileroot->hasChild($contextpath));
+
+            $json = $fileroot->getChild($contextpath)->getContent();
+            return json_decode($json);
+        };
+
+        $writer->set_context($block1context)
+            ->export_user_preference($component, $block1key, $block1value, $desc);
+        $writer->set_context($block2context)
+            ->export_user_preference($component, $block2key, $block2value, $desc);
+
+        $block1export = $retrieveexport($block1context);
+        $block2export = $retrieveexport($block2context);
+
+        // Confirm that the exports didn't write to the same file.
+        $this->assertTrue(isset($block1export->$block1key));
+        $this->assertTrue(isset($block2export->$block2key));
+        $this->assertFalse(isset($block1export->$block2key));
+        $this->assertFalse(isset($block2export->$block1key));
+        $this->assertEquals($block1value, $block1export->$block1key->value);
+        $this->assertEquals($block2value, $block2export->$block2key->value);
+    }
+
     /**
      * User preferences can be exported against the system.
      *