tool/test: accept the watcher to use for testing as an env var, WATCHER

Author: Will

.github/workflows/macos.yml

@@ -35,6 +35,8 @@ jobs:
       - uses: chetan/git-restore-mtime-action@v2
       - run: tool/build --verbose --no-run
       - run: tool/test/all
+        env:
+          WATCHER: ${{github.workspace}}/out/${{matrix.target-platform}}/Debug/wtr.watcher.asan
       - run: tool/build --verbose --no-build --no-run-perf
       - run: tool/build --verbose --no-build --no-run-unit
       - run: ls -al out/${{matrix.target-platform}}/Debug

.github/workflows/ubuntu.yml

@@ -33,6 +33,8 @@ jobs:
       - uses: chetan/git-restore-mtime-action@v2
       - run: tool/build --verbose --no-run
       - run: tool/test/all
+        env:
+          WATCHER: ${{github.workspace}}/out/${{matrix.target-platform}}/Debug/wtr.watcher.asan
       - run: tool/build --verbose --no-build --no-run-perf
       - run: tool/build --verbose --no-build --no-run-unit
       - run: ls -al out/${{matrix.target-platform}}/Debug

tool/test/.ctx

@@ -8,25 +8,21 @@
 # shellcheck disable=SC2317
 # SC2317: Command can be reached.
 
-beganat=$(date -u +"%Y-%m-%dT%H:%M:%SZ") # or date --iso=ns -u on non-bsd
-builddir=$( (cd "$(dirname "$0")/../../out" && pwd) )
-testdir=$builddir/tst-$beganat
+testdir=$(mktemp -d -t tst-XXXXXX) || exit 1
+WATCHER=$(realpath "${WATCHER:-$(command -v wtr.watcher)}") || {
+  echo WATCHER env var not set to a valid path and wtr.watcher not found in PATH 1>&2
+  exit 1
+}
 export testdir
 
 trap "cd '$PWD' ; rm -rf '$testdir' '$testdir.json'" EXIT
-mkdir -p "$testdir" || exit 1
 cd "$testdir" || exit 1
 
-PATH=$builddir/this/Debug:$PATH
-
-# Otherwise, the Darwin watcher will the testdir's creation event
+# Otherwise, the Darwin watcher will see the testdir's creation event
 [ "$(uname -s)" = Darwin ] && sleep 0.2
 
 watch-async() {
-  watcher-via-nix() { nix run --quiet .\#watcher -- "$@"; }
-  watcher=$(command -v wtr.watcher || echo 'watcher-via-nix')
-
-  "$watcher" "$@" &
+  "$WATCHER" "$@" &
   sleep 0.1
 }
 export -f watch-async