styra-link: unhandled bad download URL for styra CLI causes cryptic e…

…rror (#78)

### What code changed, and why?

With a bad URL the automatic install of the Styra CLI by the Styra
VSCode plugin still resulted in storing _something_ at
/usr/local/bin/styra, but not an executable binary(!). 
The code assumed it was the real thing, reported
the CLI installation successful(!), tried to invoke it as the styra CLI,
and said _"Error spawn Unknown system error -8"_.

This PR will now recognize that the non-empty download
was not an executable, so fails the "install" operation properly.

CHANGELOG.md

@@ -9,7 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- None
+### Fixed
+
+- Check that downloaded CLI binary is an actual binary (not a 404 page) instead of assuming it is.
+  With a bad download URL this caused a cryptic "Error spawn Unknown system error -8" message.
 
 ## [2.0.0] - 2023-09-25
 

README.md

@@ -2,7 +2,7 @@
 [![slack](https://img.shields.io/badge/slack-styra-24b6e0.svg?logo=slack)](https://styracommunity.slack.com/)
 [![Apache License](https://img.shields.io/badge/license-Apache%202.0-orange.svg)](https://www.apache.org/licenses/LICENSE-2.0)
 [![Visual Studio Marketplace Version](https://img.shields.io/visual-studio-marketplace/v/Styra.vscode-styra?color=24b6e0)](#)
-[![Coverage](https://img.shields.io/badge/Coverage-73%25-brightgreen)](#)
+[![Coverage](https://img.shields.io/badge/Coverage-72%25-brightgreen)](#)
 [![CI status](https://github.com/StyraInc/vscode-styra/actions/workflows/main.yaml/badge.svg)](https://github.com/StyraInc/vscode-styra/actions/workflows/main.yaml)
 [![closed PRs](https://img.shields.io/github/issues-pr-closed-raw/StyraInc/vscode-styra)](https://github.com/StyraInc/vscode-styra/pulls?q=is%3Apr+is%3Aclosed)
 <!--

package.json

@@ -12,7 +12,7 @@
     "url": "https://github.com/StyraInc/vscode-styra/issues"
   },
   "publisher": "styra",
-  "version": "2.0.1-next.1",
+  "version": "2.0.1-next.2",
   "private": true,
   "main": "./out/main.js",
   "engines": {

src/commands/executor.ts

@@ -15,6 +15,7 @@ export class Executor {
     }
     if (!await StyraInstall.styraCmdExists()) {
       info(`"${STYRA_CLI_CMD}" not found; aborting ${command.title}`);
+      return;
     }
     // Deliberately delay the official start of a command until here;
     // that way, any diagnostic output from the above pre-flight steps are nicely separated.

src/lib/command-runner.ts

@@ -100,7 +100,6 @@ export class CommandRunner {
     const possibleError = options?.possibleError ?? '';
     const quiet = options?.quiet ?? false;
     if (!StyraInstall.checkWorkspace()) {
-      teeError('Something is wrong! Did you forget to run checkWorkspace in your command?');
       return '';
     }
     const projectDir = IDE.projectDir();

src/lib/styra-install.ts

@@ -147,8 +147,6 @@ export class StyraInstall {
   }
 
   private static async installStyra(): Promise<void> {
-    info(`    Platform: ${process.platform}`);
-    info(`    Architecture: ${process.arch}`);
 
     const tempFileLocation = path.join(os.homedir(), this.BinaryFile);
 
@@ -167,6 +165,8 @@ export class StyraInstall {
       cancellable: false
     }, async () => {
       await this.getBinary(url, tempFileLocation);
+      info(`    Platform: ${process.platform}`);
+      info(`    Architecture: ${process.arch}`);
       info(`    Executable: ${this.ExeFile}`);
       fs.chmodSync(tempFileLocation, '755');
       if (this.isWindows()) {
@@ -185,6 +185,12 @@ export class StyraInstall {
   private static async getBinary(url: string, tempFileLocation: string): Promise<void> {
     // adapted from https://stackoverflow.com/a/69290915
     const response = await fetch(url);
+    if (!response.ok) {
+      throw new Error(
+        response.status === 404 ? `Bad URL for downloading styra - ${url}`
+          : `Error attempting to downloading styra CLI: status = ${response.status}`);
+    }
+
     const writeStream = fse.createWriteStream(tempFileLocation, {
       autoClose: true,
       flags: 'w',

src/test-jest/commands/executor.test.ts

@@ -25,9 +25,12 @@ describe('Executor', () => {
   const spy = new OutputPaneSpy();
   const spyAppendLine = jest.spyOn(outputChannel, 'appendLine');
   Executor.checkStartup = jest.fn();
-  StyraInstall.styraCmdExists = jest.fn().mockResolvedValue(true);
   IDE.getConfigValue = mockVSCodeSettings();
 
+  beforeEach(() => {
+    StyraInstall.styraCmdExists = jest.fn().mockResolvedValue(true);
+  });
+
   [
     [true, 'CONTINUES'],
     [false, 'ABORTS'],