SplitBit-Emulator/Tests/replay.sh

#!/usr/bin/env bash
# Checks that what the machine records is what it plays back.
#
# --record-pad writes what a controller held, one byte a frame, in exactly the format --pad
# reads. That symmetry is the whole feature and it is the whole of what is checked here: a
# recording is only worth having if playing it back does what was recorded.
#
# ---- Why it exists ----
#
# Some inputs cannot sensibly be written by hand. Flying a lander from one base to another is
# a few hundred frames of steering that has to arrive somewhere eight cells wide, and several
# attempts at hand-authoring one got within two columns and no closer. That is a piloting
# exercise rather than a test. Playing it once and keeping what happened is the answer, and
# this is what says the keeping works.
#
# Written by Anachronaut

set -u
ROOT="$(cd "$(dirname "$0")/.." && pwd)"
BUILD="$ROOT/Tests/build/replay"
ASM="$ROOT/Assembler"
EMU="$ROOT/SplitBit"

for tool in "$ASM" "$EMU"; do
    [ -x "$tool" ] || { echo "$(basename "$tool") is not built."; exit 1; }
done

rm -rf "$BUILD"; mkdir -p "$BUILD"

PASS=0
FAIL=0
FAILED_NAMES=()

GREEN=$'\033[32m'; RED=$'\033[31m'; RESET=$'\033[0m'
[ -t 1 ] || { GREEN=""; RED=""; RESET=""; }

result() {
    if [ "$1" = "ok" ]; then
        PASS=$((PASS + 1)); printf "  [%sok  %s] %-40s %s\n" "$GREEN" "$RESET" "$2" "$3"
    else
        FAIL=$((FAIL + 1)); FAILED_NAMES+=("$2")
        printf "  [%sFAIL%s] %-40s %s\n" "$RED" "$RESET" "$2" "$3"
    fi
}

echo "Checking that a recording plays back as itself."

# A program that reads a pad every frame and stops. It is the one in testPrograms rather than
# a new one, because what is being checked is the recording and not the reading.
"$ASM" "$ROOT/Programs/testPrograms/padTest.asm" -o "$BUILD/padTest.bin" > "$BUILD/asm.log" 2>&1 \
    || { echo "padTest did not assemble."; exit 1; }

# ---- Played and recorded at the same time ----
#
# The strongest form of the claim: the recording is made OF a playback, so if the two formats
# ever drift apart the bytes coming out stop matching the bytes going in.
"$EMU" --fast --pad "$ROOT/Tests/input/padTest.pad" \
    --record-pad "$BUILD/roundtrip.pad" "$BUILD/padTest.bin" > "$BUILD/roundtrip.out" 2>&1
SAME="$(python3 -c "
first = open('$ROOT/Tests/input/padTest.pad', 'rb').read()
again = open('$BUILD/roundtrip.pad', 'rb').read()
print('yes' if again[:len(first)] == first else 'no')
" 2>/dev/null || echo error)"
[ "$SAME" = "yes" ] \
    && result ok "a recording of a playback is the playback" "byte for byte, in and out" \
    || result no "a recording of a playback is the playback" "the bytes differ"

# ---- One byte a frame, and the frame is the machine's ----
#
# A recording is a TIMELINE. If it were a byte a read, a program that polled twice in one
# frame would record twice as fast as it flew; if it skipped frames nobody looked at, it would
# play back faster than it was flown. So the count is the number of frames the machine ran,
# which at 16,667 cycles a frame is arithmetic rather than a guess.
"$EMU" --fast --cycles 500000 --record-pad "$BUILD/timeline.pad" \
    "$BUILD/padTest.bin" > "$BUILD/timeline.out" 2>&1
WROTE="$(wc -c < "$BUILD/timeline.pad" | tr -d ' ')"
# The machine halts of its own accord well before the limit, so what is checked is that the
# count is frames-of-something rather than bytes-of-nothing: more than none, and fewer than
# the limit could possibly hold.
[ "$WROTE" -gt 0 ] && [ "$WROTE" -le 30 ] \
    && result ok "a byte for every frame and no more" "$WROTE frames of it" \
    || result no "a byte for every frame and no more" "$WROTE bytes, which is not a frame count"

# ---- And a machine with no controller records that honestly ----
#
# Nothing held is nought, which is what a pad nobody is touching reports and what a machine
# with no pad at all reports. A recorder that wrote something else would make a fixture that
# pressed buttons nobody pressed.
QUIET="$(python3 -c "
data = open('$BUILD/timeline.pad', 'rb').read()
print('yes' if set(data) <= {0} else 'no')
" 2>/dev/null || echo error)"
[ "$QUIET" = "yes" ] \
    && result ok "and nothing held is written as nothing" "no buttons nobody pressed" \
    || result no "and nothing held is written as nothing" "the recording holds something"

echo
if [ "$FAIL" -eq 0 ]; then
    echo "All $PASS replay checks passed."
    exit 0
fi
echo "$PASS passed, $FAIL failed: ${FAILED_NAMES[*]}"
exit 1