tests: add a direnv integration test

Test that simply evaluating a shell does not trigger direnv to reload
immediately.

Author: sandydoo

tests/direnv/.test.sh

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+# Test the direnv integration
+#
+# Our main concern is that `devenv shell` should not trigger direnv to immediately reload.
+# Because direnv only checks the modification time of watched files, we need to take extra care not to "carelessly" write to such files.
+set -xeuo pipefail
+
+# Install direnv
+export PATH="$(nix build nixpkgs#direnv --print-out-paths --no-out-link)/bin:$PATH"
+
+export TMPDIR=$(mktemp -d)
+export XDG_CONFIG_HOME=${TMPDIR}/config
+export XDG_DATA_HOME=${TMPDIR}/data
+
+direnv_eval() {
+  eval "$(direnv export bash)"
+}
+
+# Setup direnv
+mkdir -p $XDG_CONFIG_HOME/.config/direnv/
+cat > $XDG_CONFIG_HOME/.config/direnv/direnv.toml << 'EOF'
+[global]
+strict_env = true
+EOF
+
+# Initialize direnv
+cat > .envrc << 'EOF'
+  eval "$(devenv direnvrc)"
+  use devenv
+EOF
+
+# Load the environment
+direnv allow
+direnv_eval
+
+# Enter shell and capture initial watches
+DIRENV_WATCHES_BEFORE=$DIRENV_WATCHES
+
+# Execute some operations that should not cause direnv to reload
+echo "Running commands that should not trigger direnv reload..." >&2
+devenv shell "echo 'Hello from devenv shell'"
+
+direnv_eval
+
+# Capture watches after
+DIRENV_WATCHES_AFTER=$DIRENV_WATCHES
+
+echo "Checking whether direnv reload was triggered..." >&2
+if [[ "$DIRENV_WATCHES_BEFORE" == "$DIRENV_WATCHES_AFTER" ]]; then
+  echo "PASS: DIRENV_WATCHES remained unchanged" >&2
+  exit 0
+else
+  echo "FAIL: DIRENV_WATCHES changed, indicating unwanted reload" >&2
+  echo "Before: $DIRENV_WATCHES_BEFORE" >&2
+  echo "After:  $DIRENV_WATCHES_AFTER" >&2
+  exit 1
+fi

tests/direnv/devenv.nix

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+{ }