Revert "tests: move to _tests"

This reverts commit 4d498aff1a.

tests/eval-test.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+cd $(dirname $0)/..
+
+find=(find . -name default.nix)
+
+for profile in `${find[@]}`; do
+    echo evaluating $profile >&2
+
+    nixos-rebuild \
+	-I nixos-config=tests/eval-test.nix \
+	-I nixos-hardware-profile=$profile \
+	dry-build
+
+    if [ $? -ne 0 ]; then
+	exit 1
+    fi
+done