testsuite: Add more debug output on failure to call ghc-pkg

testsuite/driver/testutil.py

@@ -59,7 +59,7 @@ def getStdout(cmd_and_args: List[str]):
     if r != 0:
         raise Exception("Command failed: " + str(cmd_and_args))
     if stderr:
-        raise Exception("stderr from command: %s\nOutput:\n%s\n" % (cmd_and_args, stderr.decode('utf-8')))
+        raise Exception("stderr from command: %s\nStdOut(%s):\n%s\n%s\nOutput(%s):\n%s\n%s\n" % (cmd_and_args,str(len(stdout)), stdout, stdout.decode('utf-8'), str(len(stderr)), stderr, stderr.decode('utf-8')))
     return stdout.decode('utf-8')
 
 def lndir(srcdir: Path, dstdir: Path, force_copy=False):