add tests

test.js

@@ -0,0 +1,51 @@
+'use strict';
+
+var challenge = require('./').create({ debug: true, webrootPath: '/tmp/acme-challenge' });
+
+var opts = challenge.getOptions();
+var domain = 'example.com';
+var token = 'token-id';
+var key = 'secret-key';
+
+challenge.remove(opts, domain, token, function () {
+  // ignore error, if any
+
+  challenge.set(opts, domain, token, key, function (err) {
+    // if there's an error, there's a problem
+    if (err) {
+      throw err;
+    }
+
+    // throw new Error("manually check /tmp/acme-challenge");
+
+    challenge.get(opts, domain, token, function (err, _key) {
+      // if there's an error, there's a problem
+      if (err) {
+        throw err;
+      }
+
+      // should retrieve the key
+      if (key !== _key) {
+        throw new Error("FAIL: could not get key by token");
+      }
+
+      challenge.remove(opts, domain, token, function () {
+        // if there's an error, there's a problem
+        if (err) {
+          throw err;
+        }
+
+        challenge.get(opts, domain, token, function (err, _key) {
+          // error here is okay
+
+          // should NOT retrieve the key
+          if (_key) {
+            throw new Error("FAIL: should not get key");
+          }
+
+          console.info('PASS');
+        });
+      });
+    });
+  });
+});