Add lint and unit testing

.eslintrc.json

@@ -0,0 +1,16 @@
+{
+    "globals": {
+        "clearInterval": false,
+        "console": false,
+        "module": true,
+        "require": false,
+        "setInterval": false
+    },
+    "extends": "eslint:recommended",
+    "parserOptions": {
+        "ecmaVersion": 5
+    },
+    "rules": {
+        "no-console": "off"
+    }
+}

__mocks__/react-native-ntp-client.js

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+// __mocks__/react-native-ntp-client.js
+'use strict';
+
+const client = jest.genMockFromModule('react-native-ntp-client');
+
+// a fake NTP server domain that triggers the error callback in 'getNetworkTime'
+const MOCK_FAILING_SERVER = 'FAIL.FAIL.FAIL';
+
+// internal value to mock an NTP server's delta time in ms
+var __offset_ms = 0;
+
+// custom method to allow tests to set a server delta time
+// can be +/- (values in milliseconds)
+function __setOffsetMs(ms) {
+  __offset_ms = ms;
+}
+
+// custom getNetworkTime that simply calls callback
+function getNetworkTime(s, p, cb) {
+  if (cb) {
+    if (s === MOCK_FAILING_SERVER) {
+      cb(new Error('Mock Error'), null);
+    } else {
+      cb(null, new Date( Date.now() + __offset_ms ));
+    }
+  }
+}
+
+/**** mocked API ****/
+client.MOCK_FAILING_SERVER = MOCK_FAILING_SERVER;
+client.__setOffsetMs = __setOffsetMs;
+// overrides
+client.getNetworkTime = getNetworkTime;
+
+module.exports = client;