test: Add regression test for non-existent env var

.editorconfig

@@ -13,5 +13,8 @@ charset = utf-8
 [*.sh]
 indent_size = 2
 
+[*.{yaml,yml}]
+indent_size = 2
+
 [Makefile]
 indent_style = tab

.github/workflows/tests.yaml

@@ -0,0 +1,17 @@
+---
+name: 'Run Tests'
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v3
+
+      - name: 'Execute tests'
+        run: './run_tests'

.pre-commit-config.yaml

@@ -20,5 +20,4 @@ repos:
         additional_dependencies:
           - mdformat-gfm
           - mdformat-toc
-
 # EOF

tests/works_without_env

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+#
+
+unset -v XDG_DATA_HOME
+make install