Bug fix for #331 continue skips while condition check

[ahangsu]

Description

The error is caused by https://github.com/algorand/pyteal/blob/master/pyteal/ast/while_.py#L55, where continue block's next block is wired to the start of do block. Expected behavior is wire continue's next to cond's start.

The code incurring bug is

from pyteal import *

i = ScratchVar(slotId=10)
ast = Seq(
    i.store(Int(0)),
    While(i.load() < Int(30)).Do(
        Seq(
            i.store(i.load() + Int(1)),
            Continue(),
        )
    ),
    Return(Int(1))
)

comp = compileTeal(ast, Mode.Application, version=6)

print(comp)

After the bug fix, the (plausibly correct to my eyes) produced code is

#pragma version 6
int 0
store 10
main_l1:
load 10
int 30
<
bz main_l3
load 10
int 1
+
store 10
b main_l1
main_l3:
int 1
return

This PR also contains some testcase change in compiler test, relating with continue in while behavior.

Closes #331

[tzaffi]

Nice catch.

I think this is a great candidate for a graviton test and I'll be very happy to assist in this regard.,

[jasonpaulos]

This looks correct, thank you for the fix and updated tests

[tzaffi]

LGTM

Glad graviton could give greater confidence