rupprecht marked 3 inline comments as done.
rupprecht added inline comments.
================
Comment at: lldb/packages/Python/lldbsuite/test/terminal/TestEditline.py:37-38
+
+ # Run help for different commands for escape variants to make sure each
+ # one matches uniquely (the buffer isn't cleared in between matches).
+ cases = [
----------------
labath wrote:
> rupprecht wrote:
> > labath wrote:
> > > The buffer isn't exactly "cleared", but each "expect" command should only
> > > match from the end of the previous match, so repeating the same command
> > > should not be a problem. What the other (few) pexpect tests do is put an
> > > `self.expect_prompt()` to ensure all output from the previous command is
> > > ignored, and lldb is ready to receive a new command. You could do that
> > > too. In fact, you could probably use the helper "expect" command which
> > > does all of this for you:
> > > `self.expect("el ommand{L}c{L}{L}h{R}p".format(...), substrs=["Syntax:
> > > command"])`
> > The expect helper is nice, thanks!
> >
> > > but each "expect" command should only match from the end of the previous
> > > match
> > I am not able to reproduce that. If I change the expect to the static
> > string `"Syntax: print"` (not `% cmd`), then the second case (which types
> > `"help step"`) passes. Which implies it's checking the entire buffer.
> >
> > The third case (`"help exit"`) fails because the buffer does not contain
> > the `print` help text anymore. But that means this behavior is dependent on
> > the relation between help text length and buffer size. For now, I'll leave
> > this as separate help commands.
> That's very odd. It's definitely not how things behave on my end (the second
> check fails straight away), and it's not clear to me why would that differ
> for you. Looking at the code, it's pretty obvious
> <https://github.com/llvm/llvm-project/blob/b5f14326b447e5a97b3d7654448c36d7745a6882/lldb/third_party/Python/module/pexpect-4.6/pexpect/expect.py#L32>
> that pexpect intends to reset the internal buffer to include only the text
> after the last match.
>
> I'd like to get to the bottom of this. Can you dig around (maybe step through
> the pexpect code) to see what's happening in your case? One thing that's been
> causing confusion in the past was the leftover
> `third_party/Python/module/pexpect-2.X` folder from the time before we
> updated pexpect. However, I find it unlikely that this would be the case
> here, as this should have been the pexpect behavior since forever...
Figured out what was going on and mailed D70324 to prevent this from happening
to the next person this bites -- which could be me :)
I originally had:
```
self.child.send("help command\n")
self.child.expect_exact("Syntax: command")
```
And based on your suggestion, changed it to:
```
self.expect("help command\n", substrs=["Syntax: command"])
```
Which is wrong, because `self.expect()` calls `self.child.sendline(cmd)`, so
it's running `"help command\n\n"` == `"help command\nhelp command\n"`.
The `expect_prompt()` helper will match the first prompt it sees, so the second
run of the command is still in the match buffer. Checking for "Syntax: command"
would still pass even though it was not intentionally ran twice.
I also tried changing `expect_prompt()` to continuously match until the last
prompt it sees, but it's simpler to just disallow `\n` in the command.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D70137/new/
https://reviews.llvm.org/D70137
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