constants tests and documentation

src/__tests__/constants.test.js

@@ -0,0 +1,27 @@
+import {get_version, instance_id, package_json} from '../utils/constants'
+
+const uuid = require('uuid');
+
+test(`can read 'package.json'`, () => {
+  console.log(package_json);
+  expect(package_json).toBeDefined();
+});
+
+test(`'instance_id' is valid`, () => {
+  console.log(instance_id);
+  expect(instance_id).toBeDefined();
+  expect(uuid.parse(instance_id)).toBeInstanceOf(Uint8Array);
+});
+
+test(`'version' can be read from 'package.json'`, () => {
+  console.log(get_version());
+  expect(get_version()).toBe('1.3.1-r1');
+});
+
+test(`'version' can be overridden by environment variable`, () => {
+  console.log(process.env);
+  process.env.REPERTORY_JS_FORCE_VERSION = '1.3.0';
+  console.log(get_version());
+  expect(get_version()).toBe('1.3.0');
+  console.log(process.env);
+});