diff --git a/README.md b/README.md
index a419fea8..6de99878 100644
--- a/README.md
+++ b/README.md
@@ -94,6 +94,45 @@ Task Runner commands can be customized in two ways:
       this file to declare default options which are expected to work with your
       application under regular circumstances. This file should be committed in
       the project.
+    * Third parties might implement config providers to modify the config. A
+      config provider is a class implementing the `ConfigProviderInterface`.
+      Such a class should be placed under the `TaskRunner\ConfigProviders`
+      relative namespace. For instance when `Some\Namespace` points to `src/`
+      directory, then the config provider class should be placed under the
+      `src/TaskRunner/ConfigProviders` directory and will have the namespace set
+      to `Some\Namespace\TaskRunner\ConfigProviders`. The class name should end
+      with the `ConfigProvider` suffix. Use the `::provide()` method to alter
+      the configuration object. A `@priority` annotation tag can be defined in
+      the class docblock in order to determine the order in which the config
+      providers are running. If omitted, `@priority 0` is assumed. This
+      mechanism allows also to insert custom YAML config files in the flow, see
+      the following example:
+      ```
+      namespace Some\Namespace\TaskRunner\ConfigProviders;
+
+      use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+      use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+      use Robo\Config\Config;
+
+      /**
+       * @priority 100
+       */
+      class AddCustomFileConfigProvider implements ConfigProviderInterface
+      {
+          use ConfigFromFilesTrait;
+          public static function provide(Config $config): void
+          {
+              // Load the configuration from custom.yml and custom2.yml and
+              // apply it to the configuration object. This will override config
+              // from runner.yml.dist (which has priority 1500) but get
+              // overridden by the config from runner.yml (priority -1000).
+              static::importFromFiles($config, [
+                  'custom.yml',
+                  'custom2.yml',
+              ]);
+          }
+      }
+      ```
     * `runner.yml` - project specific user overrides. This file is also located
       in the root folder of the project that depends on the Task Runner. This
       file can be used to override options with values that are specific to the
diff --git a/composer.json b/composer.json
index f3f1eae9..1a6085ce 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
     "prefer-stable": true,
     "require": {
         "php": ">=7.2",
-        "consolidation/robo": "^1.4",
+        "consolidation/robo": "^1.4.7",
         "gitonomy/gitlib": "^1.0",
         "jakeasmith/http_build_url": "^1.0.1",
         "nuvoleweb/robo-config": "^0.2.1",
diff --git a/src/Commands/RunnerCommands.php b/src/Commands/RunnerCommands.php
new file mode 100644
index 00000000..b072fb3a
--- /dev/null
+++ b/src/Commands/RunnerCommands.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenEuropa\TaskRunner\Commands;
+
+use Robo\Exception\AbortTasksException;
+use Symfony\Component\Yaml\Yaml;
+
+/**
+ * Commands to interact with the task runner itself.
+ */
+class RunnerCommands extends AbstractCommands
+{
+
+    /**
+     * Displays the current configuration in YAML format.
+     *
+     * If no argument is passed the whole configuration is outputted. To display
+     * a specific configuration, pass the key as argument (e.g. `drupal.root`).
+     *
+     * @command config
+     *
+     * @param string|null $key Optional configuration key
+     * @return string
+     * @throws \Robo\Exception\AbortTasksException
+     *
+     * @todo Implement a `--format` option to allow different output formats.
+     */
+    public function config(?string $key = null): string
+    {
+        if (!$key) {
+            $config = $this->getConfig()->export();
+        } else {
+            if (!$this->getConfig()->has($key)) {
+                throw new AbortTasksException("Invalid '$key' key.");
+            }
+            $config = $this->getConfig()->get($key);
+        }
+        return trim(Yaml::dump($config, 10, 2));
+    }
+}
diff --git a/src/Contract/ConfigProviderInterface.php b/src/Contract/ConfigProviderInterface.php
new file mode 100644
index 00000000..86bd1989
--- /dev/null
+++ b/src/Contract/ConfigProviderInterface.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenEuropa\TaskRunner\Contract;
+
+use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+use Robo\Config\Config;
+
+/**
+ * Interface for configuration providers.
+ *
+ * Classes implementing this interface:
+ * - Should have `TaskRunner\ConfigProviders` as relative namespace. For
+ *   instance when `Some\Namespace` points to the `src/` directory, then the
+ *   class should be placed in `src/TaskRunner/ConfigProviders` and will have
+ *   `Some\Namespace\TaskRunner\ConfigProviders` as namespace.
+ * - The class name should end with the `ConfigProvider` suffix.
+ */
+interface ConfigProviderInterface
+{
+    /**
+     * The relative path for an environment specific config file.
+     *
+     * If this file is found in the local environment's default configuration
+     * path (such as $XDG_CONFIG_HOME or $HOME/.config/) then it will
+     * automatically be included.
+     *
+     * Any custom config providers that read config from a hierarchical data
+     * storage are suggested to use this path.
+     *
+     * @var string
+     */
+    const DEFAULT_CONFIG_LOCATION = 'openeuropa/taskrunner/runner.yml';
+
+    /**
+     * Adds or overrides configuration.
+     *
+     * Implementations should alter the `$config` object, passed to the method.
+     * A convenient way to provide additional config or override the existing
+     * one is to use the `ConfigFromFilesTrait::importFromFiles()` method and
+     * load overrides form custom config .yml files. But the $config object can
+     * be manipulated also directly using its methods, e.g. $config->().
+     *
+     * @param \Robo\Config\Config $config
+     *
+     * @see ConfigFromFilesTrait::importFromFiles()
+     */
+    public static function provide(Config $config): void;
+}
diff --git a/src/TaskRunner.php b/src/TaskRunner.php
index b71a1fe6..5c23d2b6 100644
--- a/src/TaskRunner.php
+++ b/src/TaskRunner.php
@@ -3,12 +3,17 @@
 namespace OpenEuropa\TaskRunner;
 
 use Composer\Autoload\ClassLoader;
+use Consolidation\AnnotatedCommand\Parser\Internal\DocblockTag;
+use Consolidation\AnnotatedCommand\Parser\Internal\TagFactory;
+use Consolidation\Config\Loader\ConfigProcessor;
 use Gitonomy\Git\Repository;
 use OpenEuropa\TaskRunner\Commands\ChangelogCommands;
 use OpenEuropa\TaskRunner\Commands\DrupalCommands;
 use OpenEuropa\TaskRunner\Commands\DynamicCommands;
 use OpenEuropa\TaskRunner\Commands\ReleaseCommands;
+use OpenEuropa\TaskRunner\Commands\RunnerCommands;
 use OpenEuropa\TaskRunner\Contract\ComposerAwareInterface;
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
 use OpenEuropa\TaskRunner\Contract\RepositoryAwareInterface;
 use OpenEuropa\TaskRunner\Contract\TimeAwareInterface;
 use OpenEuropa\TaskRunner\Services\Composer;
@@ -72,6 +77,7 @@ class TaskRunner
         ChangelogCommands::class,
         DrupalCommands::class,
         ReleaseCommands::class,
+        RunnerCommands::class,
     ];
 
     /**
@@ -89,11 +95,13 @@ public function __construct(InputInterface $input, OutputInterface $output, Clas
         $this->workingDir = $this->getWorkingDir($this->input);
         chdir($this->workingDir);
 
-        $this->config = $this->createConfiguration();
+        $this->config = new Config();
         $this->application = $this->createApplication();
         $this->application->setAutoExit(false);
         $this->container = $this->createContainer($this->input, $this->output, $this->application, $this->config, $classLoader);
 
+        $this->createConfiguration();
+
         // Create and initialize runner.
         $this->runner = new RoboRunner();
         $this->runner->setContainer($this->container);
@@ -150,48 +158,92 @@ public function getCommands($class)
     }
 
     /**
-     * Create default configuration.
-     *
-     * @return Config
+     * Parses the configuration files, and merges them into the Config object.
      */
     private function createConfiguration()
     {
         $config = new Config();
         $config->set('runner.working_dir', realpath($this->workingDir));
-        Robo::loadConfiguration([
-            __DIR__.'/../config/runner.yml',
-            'runner.yml.dist',
-            'runner.yml',
-            $this->getLocalConfigurationFilepath(),
-        ], $config);
-
-        return $config;
+
+        foreach ($this->getConfigProviders() as $class) {
+            /** @var \OpenEuropa\TaskRunner\Contract\ConfigProviderInterface $class */
+            $class::provide($config);
+        }
+
+        // Resolve variables and import into config.
+        $processor = (new ConfigProcessor())->add($config->export());
+        $this->config->import($processor->export());
+        // Keep the container in sync.
+        $this->container->share('config', $this->config);
     }
 
     /**
-     * Get the local configuration filepath.
+     * Discovers all config providers.
      *
-     * @param string $configuration_file
-     *   The default filepath.
+     * @return string[]
+     *   An array of fully qualified class names of available config providers.
      *
-     * @return string|null
-     *   The local configuration file path, or null if it doesn't exist.
+     * @throws \ReflectionException
+     *   Thrown if a config provider doesn't have a valid annotation.
      */
-    private function getLocalConfigurationFilepath($configuration_file = 'openeuropa/taskrunner/runner.yml')
+    private function getConfigProviders(): array
     {
-        if ($config = getenv('OPENEUROPA_TASKRUNNER_CONFIG')) {
-            return $config;
-        }
+        /** @var \Robo\ClassDiscovery\RelativeNamespaceDiscovery $discovery */
+        $discovery = Robo::service('relativeNamespaceDiscovery');
+        $discovery->setRelativeNamespace('TaskRunner\ConfigProviders')
+            ->setSearchPattern('/.*ConfigProvider\.php$/');
 
-        if ($config = getenv('XDG_CONFIG_HOME')) {
-            return $config . '/' . $configuration_file;
+        // Discover config providers.
+        foreach ($discovery->getClasses() as $class) {
+            if (is_subclass_of($class, ConfigProviderInterface::class)) {
+                $classes[$class] = $this->getConfigProviderPriority($class);
+            }
         }
 
-        if ($home = getenv('HOME')) {
-            return getenv('HOME') . '/.config/' . $configuration_file;
-        }
+        // High priority modifiers run first.
+        arsort($classes, SORT_NUMERIC);
 
-        return null;
+        return array_keys($classes);
+    }
+
+    /**
+     * @param string $class
+     * @return float
+     * @throws \ReflectionException
+     */
+    private function getConfigProviderPriority($class)
+    {
+        $priority = 0.0;
+        $reflectionClass = new \ReflectionClass($class);
+        if ($docBlock = $reflectionClass->getDocComment()) {
+            // Remove the leading /** and the trailing */
+            $docBlock = preg_replace('#^\s*/\*+\s*#', '', $docBlock);
+            $docBlock = preg_replace('#\s*\*+/\s*#', '', $docBlock);
+
+            // Nothing left? Exit.
+            if (empty($docBlock)) {
+                return $priority;
+            }
+
+            $tagFactory = new TagFactory();
+            foreach (explode("\n", $docBlock) as $row) {
+                // Remove trailing whitespace and leading space + '*'s
+                $row = rtrim($row);
+                $row = preg_replace('#^[ \t]*\**#', '', $row);
+                $tagFactory->parseLine($row);
+            }
+
+            $priority = array_reduce($tagFactory->getTags(), function ($priority, DocblockTag $tag) {
+                if ($tag->getTag() === 'priority') {
+                    $value = $tag->getContent();
+                    if (is_numeric($value)) {
+                        $priority = (float) $value;
+                    }
+                }
+                return $priority;
+            }, $priority);
+        }
+        return $priority;
     }
 
     /**
diff --git a/src/TaskRunner/ConfigProviders/DefaultConfigProvider.php b/src/TaskRunner/ConfigProviders/DefaultConfigProvider.php
new file mode 100644
index 00000000..f1483dca
--- /dev/null
+++ b/src/TaskRunner/ConfigProviders/DefaultConfigProvider.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenEuropa\TaskRunner\TaskRunner\ConfigProviders;
+
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+use Robo\Config\Config;
+
+/**
+ * Provides the basic default configuration for the task runner.
+ *
+ * This will import the following files:
+ * - The example configuration provided in the task runner library itself.
+ * - The default configuration "runner.yml.dist" shipped in the root folder of
+ *   the project which uses the task runner.
+ *
+ * This serves as a safe default implementation which can be overridden by
+ * environment specific configuration and user preferences.
+ *
+ * The config provider priority is very high in order to ensure that will run at
+ * the very beginning. However, in some very special circumstances, third-party
+ * config providers are abie to set priorities higher than this.
+ *
+ * @priority 1500
+ */
+class DefaultConfigProvider implements ConfigProviderInterface
+{
+    use ConfigFromFilesTrait;
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function provide(Config $config): void
+    {
+        static::importFromFiles($config, [
+            __DIR__.'/../../../config/runner.yml',
+            'runner.yml.dist',
+        ]);
+    }
+}
diff --git a/src/TaskRunner/ConfigProviders/FileFromEnvironmentConfigProvider.php b/src/TaskRunner/ConfigProviders/FileFromEnvironmentConfigProvider.php
new file mode 100644
index 00000000..4beda74b
--- /dev/null
+++ b/src/TaskRunner/ConfigProviders/FileFromEnvironmentConfigProvider.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenEuropa\TaskRunner\TaskRunner\ConfigProviders;
+
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+use Robo\Config\Config;
+
+/**
+ * Provides configuration for the local environment.
+ *
+ * This will look in the following locations, and will apply the configuration
+ * of the first found file. Any subsequent matches will be ignored.
+ *
+ * 1. Location specified in the OPENEUROPA_TASKRUNNER_CONFIG environment variable.
+ * 2. Location following the freedesktop.org specification:
+ *    ${XDG_CONFIG_HOME}/openeuropa/taskrunner/runner.yml
+ * 3. The configuration in the user's home folder:
+ *    {$HOME}/.config/openeuropa/taskrunner/runner.yml
+ *
+ * The config provider priority is very low to make sure this config provider
+ * runs at the very end, being able override configurations from all other
+ * providers in the chain. However, in some very special circumstances,
+ * third-party config providers are still abie to set priorities lower than
+ * this, making possible to override even config provided by this plugin.
+ *
+ * @priority -1500
+ */
+class FileFromEnvironmentConfigProvider implements ConfigProviderInterface
+{
+    use ConfigFromFilesTrait;
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function provide(Config $config): void
+    {
+        if ($yamlFile = static::getLocalConfigurationFilepath()) {
+            static::importFromFiles($config, [$yamlFile]);
+        }
+    }
+
+    /**
+     * Gets the configuration filepath from environment variables.
+     *
+     * @return string|null
+     *   The local configuration file path, or null if it doesn't exist.
+     */
+    private static function getLocalConfigurationFilepath(): ?string
+    {
+        if ($config = getenv('OPENEUROPA_TASKRUNNER_CONFIG')) {
+            return $config;
+        }
+
+        if ($config = getenv('XDG_CONFIG_HOME')) {
+            return $config . '/' . static::DEFAULT_CONFIG_LOCATION;
+        }
+
+        if ($home = getenv('HOME')) {
+            return getenv('HOME') . '/.config/' . static::DEFAULT_CONFIG_LOCATION;
+        }
+
+        return null;
+    }
+}
diff --git a/src/TaskRunner/ConfigProviders/LocalFileConfigProvider.php b/src/TaskRunner/ConfigProviders/LocalFileConfigProvider.php
new file mode 100644
index 00000000..94d642ce
--- /dev/null
+++ b/src/TaskRunner/ConfigProviders/LocalFileConfigProvider.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OpenEuropa\TaskRunner\TaskRunner\ConfigProviders;
+
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+use Robo\Config\Config;
+
+/**
+ * Provides local configuration.
+ *
+ * Developers working on projects using the task runner can put a "runner.yml"
+ * file in the root directory of the project and provide any local configuration
+ * overrides in this file. The file is meant for personal use and should be
+ * added to .gitignore so it will not accidentally be committed.
+ *
+ * The config provider has significant low priority in order to ensure that will
+ * run after all the third-party providers, making possible to override them,
+ * but will run before FileFromEnvironmentConfigProvider, ensuring that
+ * environment variables have the last word.
+ *
+ * @priority -1000
+ */
+class LocalFileConfigProvider implements ConfigProviderInterface
+{
+    use ConfigFromFilesTrait;
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function provide(Config $config): void
+    {
+        static::importFromFiles($config, ['runner.yml']);
+    }
+}
diff --git a/src/Traits/ConfigFromFilesTrait.php b/src/Traits/ConfigFromFilesTrait.php
new file mode 100644
index 00000000..c5df5272
--- /dev/null
+++ b/src/Traits/ConfigFromFilesTrait.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace OpenEuropa\TaskRunner\Traits;
+
+use Consolidation\Config\Loader\YamlConfigLoader;
+use Dflydev\DotAccessData\Util;
+use Robo\Config\Config;
+
+/**
+ * Reusable code for loading configuration stored in files.
+ */
+trait ConfigFromFilesTrait
+{
+    /**
+     * Loads configuration from YAML files and merges it in the given config object.
+     *
+     * @param \Robo\Config\Config $config
+     *   The configuration object to update.
+     * @param array $files
+     *   An array of paths to configuration files in YAML format.
+     */
+    private static function importFromFiles(Config $config, array $files)
+    {
+        $loader = new YamlConfigLoader();
+        foreach ($files as $file) {
+            $configArray = Util::mergeAssocArray($config->export(), $loader->load($file)->export());
+            $config->replace($configArray);
+        }
+    }
+}
diff --git a/tests/CommandsTest.php b/tests/CommandsTest.php
index 6f5478dc..2a71fcd0 100644
--- a/tests/CommandsTest.php
+++ b/tests/CommandsTest.php
@@ -343,15 +343,9 @@ public function testWorkingDirectoryToken()
      */
     public function testUserConfigFile()
     {
-        $fixtureName = 'userconfig.yml';
-
-        // Create a runner.
-        $input = new StringInput('list --working-dir=' . $this->getSandboxRoot());
-        $runner = new TaskRunner($input, new NullOutput(), $this->getClassLoader());
-        $runner->run();
-
-        // Extract a value from the default configuration.
-        $drupalRoot = $runner->getConfig()->get('drupal.root');
+        // Create a local config file.
+        $runnerYaml = $this->getSandboxRoot().'/runner.yml';
+        file_put_contents($runnerYaml, Yaml::dump(['foo' => 'baz']));
 
         // Add the environment setting.
         putenv('OPENEUROPA_TASKRUNNER_CONFIG=' . __DIR__ . '/fixtures/userconfig.yml');
@@ -359,14 +353,28 @@ public function testUserConfigFile()
         // Create a new runner.
         $input = new StringInput('list --working-dir=' . $this->getSandboxRoot());
         $runner = new TaskRunner($input, new NullOutput(), $this->getClassLoader());
-        $runner->run();
 
-        // Get the content of the fixture.
-        $content = $this->getFixtureContent($fixtureName);
+        // Set as `build` by `config/runner.yml`.
+        // Overwritten as `drupal` by `tests/fixtures/userconfig.yml`.
+        $this->assertEquals('drupal', $runner->getConfig()->get('drupal.root'));
+
+        // Set as `['root' => 'drupal']` by `TestConfigProvider::provide()`.
+        // Overwritten as `['root' => 'wordpress']` by `userconfig.yml`.
+        $this->assertSame(['root' => 'wordpress'], $runner->getConfig()->get('wordpress'));
+
+        // Set as `['root' => 'joomla']` by `tests/fixtures/third_party.yml`.
+        $this->assertSame(['root' => 'joomla'], $runner->getConfig()->get('joomla'));
+
+        // Set as `overwritten by edge case` by `tests/fixtures/userconfig.yml`.
+        // Overwritten as `overwritten` by `EdgeCaseConfigProvider::provide()`.
+        $this->assertSame('overwritten', $runner->getConfig()->get('whatever'));
 
-        $this->assertEquals($content['wordpress'], $runner->getConfig()->get('wordpress'));
-        $this->assertEquals($content['drupal']['root'], $runner->getConfig()->get('drupal.root'));
-        $this->assertNotEquals($drupalRoot, $runner->getConfig()->get('drupal.root'));
+        // The `qux` value is computed by using the `${foo}` token. We test
+        // that the replacements are done at the very end, when all the config
+        // providers had the chance to resolve the tokens. `${foo}` equals
+        // `bar`, in the `tests/fixtures/third_party.yml` file but is
+        // overwritten at the end, in `tests/sandbox/runner.yml` with `baz`.
+        $this->assertSame('is-baz', $runner->getConfig()->get('qux'));
     }
 
     /**
diff --git a/tests/custom/src/TaskRunner/ConfigProviders/EdgeCaseConfigProvider.php b/tests/custom/src/TaskRunner/ConfigProviders/EdgeCaseConfigProvider.php
new file mode 100644
index 00000000..0c976f95
--- /dev/null
+++ b/tests/custom/src/TaskRunner/ConfigProviders/EdgeCaseConfigProvider.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace My\Custom\TaskRunner\ConfigProviders;
+
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+use Robo\Config\Config;
+
+/**
+ * We set here a very low priority to run even after the default providers. This
+ * is here just as proof that the default providers can be also overridden.
+ *
+ * @priority -2000
+ */
+class EdgeCaseConfigProvider implements ConfigProviderInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public static function provide(Config $config): void
+    {
+        $config->set('whatever', 'overwritten');
+    }
+}
diff --git a/tests/custom/src/TaskRunner/ConfigProviders/TestConfigProvider.php b/tests/custom/src/TaskRunner/ConfigProviders/TestConfigProvider.php
new file mode 100644
index 00000000..7b88bbef
--- /dev/null
+++ b/tests/custom/src/TaskRunner/ConfigProviders/TestConfigProvider.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace My\Custom\TaskRunner\ConfigProviders;
+
+use OpenEuropa\TaskRunner\Contract\ConfigProviderInterface;
+use OpenEuropa\TaskRunner\Traits\ConfigFromFilesTrait;
+use Robo\Config\Config;
+
+/**
+ * @priority 1
+ */
+class TestConfigProvider implements ConfigProviderInterface
+{
+    use ConfigFromFilesTrait;
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function provide(Config $config): void
+    {
+        // This value is overridden with values from userconfig.yml.
+        $config->set('whatever.root', 'drupal');
+        // Interleave third_party.yml between runner.yml.dist and runner.yml.
+        static::importFromFiles($config, [
+            __DIR__ . '/../../../../fixtures/third_party.yml',
+        ]);
+    }
+}
diff --git a/tests/fixtures/third_party.yml b/tests/fixtures/third_party.yml
new file mode 100644
index 00000000..32dcc9d9
--- /dev/null
+++ b/tests/fixtures/third_party.yml
@@ -0,0 +1,7 @@
+joomla:
+  root: joomla
+
+foo: bar
+# Should be 'is-baz' as the variables should be resolved only at the end, when
+# all config providers had the chance to provide token values.
+qux: is-${foo}
diff --git a/tests/fixtures/userconfig.yml b/tests/fixtures/userconfig.yml
index c0e02103..be93de1c 100644
--- a/tests/fixtures/userconfig.yml
+++ b/tests/fixtures/userconfig.yml
@@ -3,3 +3,5 @@ drupal:
 
 wordpress:
   root: "wordpress"
+
+whatever: 'this will be overwritten by the edge case provider'