feat: Add database fixtures for testing migrations (#4858)

coderd/database/migrations/create_fixture.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+# Naming the fixture is optional, if missing, the name of the latest
+# migration will be used.
+#
+# Usage:
+# ./create_fixture
+# ./create_fixture name of fixture
+# ./create_fixture "name of fixture"
+# ./create_fixture name_of_fixture
+
+set -euo pipefail
+
+SCRIPT_DIR=$(dirname "${BASH_SOURCE[0]}")
+(
+	cd "$SCRIPT_DIR"
+
+	latest_migration=$(basename "$(find . -maxdepth 1 -name "*.up.sql" | sort -n | tail -n 1)")
+	if [[ -n "${*}" ]]; then
+		name=$*
+		name=${name// /_}
+		num=${latest_migration%%_*}
+		latest_migration="${num}_${name}.up.sql"
+	fi
+
+	filename="$(pwd)/testdata/fixtures/$latest_migration"
+	touch "$filename"
+	echo "$filename"
+	echo "Edit fixture and commit it."
+)