Test for presence of shadowenv binary before running Shadowenv suite

Not all non-Shopify developer environments have a version of shadowenv
installed. In those circumstances, skip the suite with a console warning.

Part of Shopify#2877

Author: adam12

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

@@ -3,6 +3,7 @@ import fs from "fs";
 import assert from "assert";
 import path from "path";
 import os from "os";
+import { execSync } from "child_process";
 
 import { beforeEach, afterEach } from "mocha";
 import * as vscode from "vscode";
@@ -14,13 +15,21 @@ import { LOG_CHANNEL, asyncExec } from "../../../common";
 import { RUBY_VERSION } from "../../rubyVersion";
 import * as common from "../../../common";
 
-suite("Shadowenv", () => {
+suite("Shadowenv", async () => {
   if (os.platform() === "win32") {
     // eslint-disable-next-line no-console
     console.log("Skipping Shadowenv tests on Windows");
     return;
   }
 
+  try {
+    execSync("shadowenv --version >/dev/null 2>&1");
+  } catch {
+    // eslint-disable-next-line no-console
+    console.log("Skipping Shadowenv tests because no `shadowenv` found");
+    return;
+  }
+
   let rootPath: string;
   let workspacePath: string;
   let workspaceFolder: vscode.WorkspaceFolder;