More CI debugging: print stderr on failure

create-neon/dev/expect.ts

@@ -1,6 +1,7 @@
 import { ChildProcess } from 'child_process';
 import { PassThrough, Readable, Writable } from 'stream';
 import { StringDecoder } from 'string_decoder';
+import readStream from 'stream-to-string';
 
 function readChunks(input: Readable): Readable {
   let output = new PassThrough({ objectMode: true });
@@ -96,13 +97,15 @@ export default async function expect(child: ChildProcess, script: Record<string,
   for await (let lines of run(script, child.stdin!, child.stdout!)) {
     output.push(lines);
   }
+  let stderr = await readStream(child.stderr!);
   let code = await exit(child);
   switch (code) {
     case null:
       throw new ChildError("child process interrupted", output);
     case 0:
       return;
     default:
+      console.log("stderr: " + stderr);
       throw new ChildError("child process exited with code " + code, output);
   }
 }

create-neon/package.json

@@ -38,6 +38,7 @@
     "execa": "^5.0.0",
     "mocha": "^8.3.1",
     "rimraf": "^3.0.2",
+    "stream-to-string": "^1.2.0",
     "toml": "^3.0.0",
     "ts-node": "^9.1.1",
     "typescript": "^4.2.2"

create-neon/test/create-neon.ts

@@ -50,7 +50,7 @@ describe('Project creation', () => {
         'Is this OK?':     ''
       });
     } catch (error) {
-      console.log(error.output);
+      console.log("stdout lines: " + error.output);
       assert.fail("create-neon unexpectedly failed: " + error.message);
     }