Use local executables when working on the Ruby LSP

vscode/src/ruby.ts

@@ -186,6 +186,20 @@ export class Ruby implements RubyInterface {
     if (!this.error) {
       this.fetchRubyVersionInfo();
       await this.setupBundlePath();
+
+      // When working on the Ruby LSP itself, we want to use the local version of our executables rather than the ones
+      // globally installed. That allows us to catch mistakes made in the launch process before they are released
+      if (
+        path.basename(this.workspaceFolder.uri.fsPath) === "ruby-lsp" &&
+        os.platform() !== "win32"
+      ) {
+        const localExecutablesUri = vscode.Uri.joinPath(
+          this.workspaceFolder.uri,
+          "exe",
+        );
+
+        this._env.PATH = `${localExecutablesUri.fsPath}${path.delimiter}${this._env.PATH}`;
+      }
     }
   }
 

vscode/src/test/suite/ruby.test.ts

@@ -1,6 +1,7 @@
 /* eslint-disable no-process-env */
 import * as assert from "assert";
 import * as path from "path";
+import os from "os";
 
 import * as vscode from "vscode";
 import sinon from "sinon";
@@ -167,4 +168,45 @@ suite("Ruby environment activation", () => {
 
     assert.deepStrictEqual(ruby.env, { BUNDLE_GEMFILE: ".ruby-lsp/Gemfile" });
   });
+
+  test("Adds local exe directory to PATH when working on the Ruby LSP itself", async () => {
+    if (os.platform() === "win32") {
+      // We don't mutate the path on Windows
+      return;
+    }
+
+    const manager = process.env.CI
+      ? ManagerIdentifier.None
+      : ManagerIdentifier.Chruby;
+
+    const configStub = sinon
+      .stub(vscode.workspace, "getConfiguration")
+      .returns({
+        get: (name: string) => {
+          if (name === "rubyVersionManager") {
+            return { identifier: manager };
+          } else if (name === "bundleGemfile") {
+            return "";
+          }
+
+          return undefined;
+        },
+      } as unknown as vscode.WorkspaceConfiguration);
+
+    const workspacePath = path.dirname(
+      path.dirname(path.dirname(path.dirname(__dirname))),
+    );
+    const lspFolder: vscode.WorkspaceFolder = {
+      uri: vscode.Uri.file(workspacePath),
+      name: path.basename(workspacePath),
+      index: 0,
+    };
+    const ruby = new Ruby(context, lspFolder, outputChannel, FAKE_TELEMETRY);
+    await ruby.activateRuby();
+
+    const firstEntry = ruby.env.PATH!.split(path.delimiter)[0];
+    assert.match(firstEntry, /ruby-lsp\/exe$/);
+
+    configStub.restore();
+  }).timeout(10000);
 });