Attempt to resolve relative plugin paths from extended config location

docs/pages/docs/configuration/autorc.mdx

@@ -362,7 +362,9 @@ The following removes the default internal and documentation label sections:
 
 ## Extending
 
-If you want to share your auto configuration between projects you can use the `extends` property. This property will load from a module's package.json or from a custom path. It's expected that the extended configuration be under the `auto` key in the package.json file.
+If you want to share your auto configuration between projects you can use the `extends` property.
+This property will load from a module's `package.json` or from a custom path.
+It's expected that the extended configuration be under the `auto` key in the `package.json` file.
 
 Auto can load `extends` configs in the following ways:
 
@@ -371,6 +373,8 @@ Auto can load `extends` configs in the following ways:
 - from a package `auto-config-YOUR_NAME`
 - from a url `https://yourdomain.com/auto-config.json` (must return the content type `application/json`)
 
+### Formats
+
 ```json
 {
   "extends": "@YOUR_SCOPE"
@@ -402,3 +406,22 @@ If you're extending from a local file it can be any file in JSON format or a `pa
   "extends": "./path/to/other/package.json"
 }
 ```
+
+### Custom Plugins
+
+An `extends` configuration can include custom plugins in the NPM package.
+This is useful if you have a shared plugin that doesn't necessarily need to be published as it's own package.
+
+> NOTE: This does not work for `auto` configs stored in a url.
+
+To include custom plugins just use a relative path in the extended configuration/
+
+**`package.json`:**
+
+```json
+{
+  "auto": {
+    "plugins": ["./plugins/some-plugin.js"]
+  }
+}
+```

packages/core/src/auto.ts

@@ -2057,7 +2057,15 @@ export default class Auto {
         extendedLocation = require.resolve(config.extends);
       }
     } catch (error) {
-      this.logger.veryVerbose.error(error);
+      try {
+        if (config.extends) {
+          extendedLocation = require.resolve(
+            path.join(process.cwd(), config.extends)
+          );
+        }
+      } catch (error) {
+        this.logger.veryVerbose.error(error);
+      }
     }
 
     return extendedLocation;

packages/core/src/utils/__tests__/load-plugin.test.ts

@@ -3,7 +3,7 @@ import endent from "endent";
 import { execSync } from "child_process";
 
 import { getInstalledPlugins, loadPlugin, listPlugins } from "../load-plugins";
-import { dummyLog } from "../logger";
+import { dummyLog, setLogLevel } from "../logger";
 
 const logger = dummyLog();
 
@@ -40,6 +40,10 @@ jest.mock(
 );
 
 describe("loadPlugins", () => {
+  beforeEach(() => {
+    setLogLevel('quiet');
+  });
+
   test("should load official plugins", () => {
     expect(loadPlugin(["baz", {}], logger)?.name).toBe("baz");
     expect(loadPlugin(["@auto-it/baz", {}], logger)?.name).toBe("baz");
@@ -50,6 +54,26 @@ describe("loadPlugins", () => {
     expect(loadPlugin(["auto-plugin-foo", {}], logger)?.name).toBe("foo");
   });
 
+  test("should load plugin stored relative to extended config package.json", () => {
+    expect(
+      loadPlugin(
+        ["./some-plugin.js", {}],
+        logger,
+        path.join(__dirname, "../test-config/package.json")
+      )?.name
+    ).toBe("test-1");
+  });
+
+  test("should load plugin stored relative to extended config dir", () => {
+    expect(
+      loadPlugin(
+        ["./some-other-plugin.js", {}],
+        logger,
+        path.join(__dirname, "../test-config")
+      )?.name
+    ).toBe("test-2");
+  });
+
   test("should load scoped plugins", () => {
     expect(loadPlugin(["@my-scope/auto-plugin-bar", {}], logger)?.name).toBe(
       "bar"

packages/core/src/utils/load-plugins.ts

@@ -128,14 +128,24 @@ export function findPlugin(
 
   // Try requiring a path from cwd
   if (isLocal) {
-    const localPath = path.join(process.cwd(), pluginPath);
-
-    if (!exists(localPath)) {
-      logger.log.warn(`Could not find plugin from path: ${localPath}`);
-      return;
+    let localPath = path.join(process.cwd(), pluginPath);
+
+    if (exists(localPath)) {
+      return localPath;
+    } 
+
+    if (extendedLocation) {
+      localPath = path.join(
+        extendedLocation.endsWith("package.json")
+          ? path.dirname(extendedLocation)
+          : extendedLocation,
+        pluginPath
+      );
+
+      if (exists(localPath)) {
+        return localPath;
+      }
     }
-
-    return localPath;
   }
 
   // For pkg bundle

packages/core/src/utils/test-config/package.json

@@ -0,0 +1,8 @@
+{
+  "auto": {
+    "plugins": [
+      "./some-other-plugin.js",
+      ["./some-plugin.js", {"foo": "bar"}]
+    ]
+  }
+}

packages/core/src/utils/test-config/some-other-plugin.js

@@ -0,0 +1,13 @@
+module.exports = class TestPlugin {
+  /**  */
+  constructor() {
+    this.name = "test-2";
+  }
+
+  /**
+   * Tap into auto plugin points.
+   */
+  apply() {
+    /** */
+  }
+};

packages/core/src/utils/test-config/some-plugin.js

@@ -0,0 +1,13 @@
+module.exports = class TestPlugin {
+  /**  */
+  constructor() {
+    this.name = "test-1";
+  }
+
+  /**
+   * Tap into auto plugin points.
+   */
+  apply() {
+    /** */
+  }
+};