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#!/usr/bin/env bash
# Property tests for the `lib.path` library
#
# It generates random path-like strings and runs the functions on
# them, checking that the expected laws of the functions hold
set -euo pipefail
shopt -s inherit_errexit
# https://stackoverflow.com/a/246128
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
if test -z "${TEST_LIB:-}"; then
TEST_LIB=$SCRIPT_DIR/../..
fi
tmp="$(mktemp -d)"
clean_up() {
rm -rf "$tmp"
}
trap clean_up EXIT
mkdir -p "$tmp/work"
cd "$tmp/work"
# Defaulting to a random seed but the first argument can override this
seed=${1:-$RANDOM}
echo >&2 "Using seed $seed, use \`lib/path/tests/prop.sh $seed\` to reproduce this result"
# The number of random paths to generate. This specific number was chosen to
# be fast enough while still generating enough variety to detect bugs.
count=500
debug=0
# debug=1 # print some extra info
# debug=2 # print generated values
# Fine tuning parameters to balance the number of generated invalid paths
# to the variance in generated paths.
extradotweight=64 # Larger value: more dots
extraslashweight=64 # Larger value: more slashes
extranullweight=16 # Larger value: shorter strings
die() {
echo >&2 "test case failed: " "$@"
exit 1
}
if [[ "$debug" -ge 1 ]]; then
echo >&2 "Generating $count random path-like strings"
fi
# Read stream of null-terminated strings entry-by-entry into bash,
# write it to a file and the `strings` array.
declare -a strings=()
mkdir -p "$tmp/strings"
while IFS= read -r -d $'\0' str; do
printf "%s" "$str" > "$tmp/strings/${#strings[@]}"
strings+=("$str")
done < <(awk \
-f "$SCRIPT_DIR"/generate.awk \
-v seed="$seed" \
-v count="$count" \
-v extradotweight="$extradotweight" \
-v extraslashweight="$extraslashweight" \
-v extranullweight="$extranullweight")
if [[ "$debug" -ge 1 ]]; then
echo >&2 "Trying to normalise the generated path-like strings with Nix"
fi
# Precalculate all normalisations with a single Nix call. Calling Nix for each
# string individually would take way too long
nix-instantiate --eval --strict --json \
--argstr libpath "$TEST_LIB" \
--argstr dir "$tmp/strings" \
"$SCRIPT_DIR"/prop.nix \
>"$tmp/result.json"
# Uses some jq magic to turn the resulting attribute set into an associative
# bash array assignment
declare -A normalised_result="($(jq '
to_entries
| map("[\(.key | @sh)]=\(.value | @sh)")
| join(" \n")' -r < "$tmp/result.json"))"
# Looks up a normalisation result for a string
# Checks that the normalisation is only failing iff it's an invalid subpath
# For valid subpaths, returns 0 and prints the normalisation result
# For invalid subpaths, returns 1
normalise() {
local str=$1
# Uses the same check for validity as in the library implementation
if [[ "$str" == "" || "$str" == /* || "$str" =~ ^(.*/)?\.\.(/.*)?$ ]]; then
valid=
else
valid=1
fi
normalised=${normalised_result[$str]}
# An empty string indicates failure, this is encoded in ./prop.nix
if [[ -n "$normalised" ]]; then
if [[ -n "$valid" ]]; then
echo "$normalised"
else
die "For invalid subpath \"$str\", lib.path.subpath.normalise returned this result: \"$normalised\""
fi
else
if [[ -n "$valid" ]]; then
die "For valid subpath \"$str\", lib.path.subpath.normalise failed"
else
if [[ "$debug" -ge 2 ]]; then
echo >&2 "String \"$str\" is not a valid subpath"
fi
# Invalid and it correctly failed, we let the caller continue if they catch the exit code
return 1
fi
fi
}
# Intermediate result populated by test_idempotency_realpath
# and used in test_normalise_uniqueness
#
# Contains a mapping from a normalised subpath to the realpath result it represents
declare -A norm_to_real
test_idempotency_realpath() {
if [[ "$debug" -ge 1 ]]; then
echo >&2 "Checking idempotency of each result and making sure the realpath result isn't changed"
fi
# Count invalid subpaths to display stats
invalid=0
for str in "${strings[@]}"; do
if ! result=$(normalise "$str"); then
((invalid++)) || true
continue
fi
# Check the law that it doesn't change the result of a realpath
mkdir -p -- "$str" "$result"
real_orig=$(realpath -- "$str")
real_norm=$(realpath -- "$result")
if [[ "$real_orig" != "$real_norm" ]]; then
die "realpath of the original string \"$str\" (\"$real_orig\") is not the same as realpath of the normalisation \"$result\" (\"$real_norm\")"
fi
if [[ "$debug" -ge 2 ]]; then
echo >&2 "String \"$str\" gets normalised to \"$result\" and file path \"$real_orig\""
fi
norm_to_real["$result"]="$real_orig"
done
if [[ "$debug" -ge 1 ]]; then
echo >&2 "$(bc <<< "scale=1; 100 / $count * $invalid")% of the total $count generated strings were invalid subpath strings, and were therefore ignored"
fi
}
test_normalise_uniqueness() {
if [[ "$debug" -ge 1 ]]; then
echo >&2 "Checking for the uniqueness law"
fi
for norm_p in "${!norm_to_real[@]}"; do
real_p=${norm_to_real["$norm_p"]}
for norm_q in "${!norm_to_real[@]}"; do
real_q=${norm_to_real["$norm_q"]}
# Checks normalisation uniqueness law for each pair of values
if [[ "$norm_p" != "$norm_q" && "$real_p" == "$real_q" ]]; then
die "Normalisations \"$norm_p\" and \"$norm_q\" are different, but the realpath of them is the same: \"$real_p\""
fi
done
done
}
test_idempotency_realpath
test_normalise_uniqueness
echo >&2 tests ok
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