Add script for students' local Linux testing

bin/test-local-gdscript-solution.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -e
+
+# Script for testing a student's local solution to a single GDScript exercise.
+# 
+# This script is intended to be run from any exercise subdirectory from the
+# Exercism GDScript track, but can live one directory higher than the
+# exercise subdirectories for convenience.
+
+slug=$(basename "$(pwd)")
+missing_gd_msg="Normally, the exercise subdirectory created by the exercism download command should contain this file."
+general_help_msg="Please see https://exercism.org/docs/tracks/gdscript/installation for details."
+if [ ! -f "${slug//-/_}_test.gd" ]; then
+    echo "Missing test file: ${slug//-/_}_test.gd"
+    echo $missing_gd_msg
+    echo $general_help_msg
+    exit 1
+fi
+if [ ! -f "${slug//-/_}.gd" ]; then
+    echo "Missing solution file: ${slug//-/_}.gd"
+    echo $missing_gd_msg
+    echo $general_help_msg
+    exit 1
+fi
+if [ ! -f "/opt/exercism/gdscript/test-runner/bin/run.sh" ]; then
+    echo "Missing test runner file: /opt/exercism/gdscript/test-runner/bin/run.sh"
+    echo $general_help_msg
+    exit 1
+fi
+
+solution_dir="$(pwd)"
+output_dir="${solution_dir}/.test-output"
+results_file="${output_dir}/results.json"
+mkdir -p "${output_dir}"
+
+(cd /opt/exercism/gdscript/test-runner && bin/run.sh "$slug" "$solution_dir" "$output_dir") || {
+    echo "Test runner script failed."
+    exit 1
+}
+
+test_status="$(jq -r '.status' "${results_file}")"
+if [ "$test_status" != "pass" ]; then
+    echo "Tests for $slug have failed:"
+    cat "${results_file}"
+    exit 1
+else
+    echo
+    echo "Tests for $slug passed!"
+fi