test: improve legacy-cli sub-process error messages

Author: jbedard

tests/legacy-cli/e2e/utils/process.ts

@@ -88,23 +88,24 @@ function _exec(options: ExecOptions, cmd: string, args: string[]): Promise<Proce
   return new Promise((resolve, reject) => {
     let matched = false;
 
-    childProcess.on('exit', (error: any) => {
+    childProcess.on('exit', (error, signal) => {
       _processes = _processes.filter((p) => p !== childProcess);
 
-      if (options.waitForMatch && !matched) {
-        error = `Output didn't match '${options.waitForMatch}'.`;
-      }
-
       if (!error) {
         resolve({ stdout, stderr });
         return;
       }
 
+      let errorMsg = `Exit[${error}]Signal[${signal}]`;
+      if (options.waitForMatch && !matched) {
+        errorMsg = `Output didn't match '${options.waitForMatch}'.`;
+      }
+
       reject(
         new Error(
           `Running "${cmd} ${args.join(
             ' ',
-          )}" returned error. ${error}...\n\nSTDOUT:\n${stdout}\n\nSTDERR:\n${stderr}\n`,
+          )}" returned error. ${errorMsg}...\n\nSTDOUT:\n${stdout}\n\nSTDERR:\n${stderr}\n`,
         ),
       );
     });