chore(stop): abstract instance getter to its own utility

lib/commands/stop.js

@@ -19,28 +19,23 @@ class StopCommand extends Command {
     }
 
     run(argv) {
-        const errors = require('../errors');
         const ProcessManager = require('../process-manager');
-        const checkValidInstall = require('../utils/check-valid-install');
+        const getInstance = require('../utils/get-instance');
 
         const runOptions = {quiet: argv.quiet};
 
         if (argv.all) {
             return this.stopAll();
         }
 
-        const instance = this.system.getInstance(argv.name);
+        let instance;
 
-        if (argv.name) {
-            if (!instance) {
-                return Promise.reject(new errors.SystemError(`Ghost instance '${argv.name}' does not exist`));
-            }
-
-            process.chdir(instance.dir);
+        try {
+            instance = getInstance(argv.name, this.system, 'stop');
+        } catch (error) {
+            return Promise.reject(error);
         }
 
-        checkValidInstall('stop');
-
         return instance.running().then((isRunning) => {
             if (!isRunning) {
                 this.ui.log('Ghost is already stopped! Nothing to do here.', 'green');

lib/utils/get-instance.js

@@ -0,0 +1,22 @@
+'use strict';
+
+const checkValidInstall = require('./check-valid-install');
+const {SystemError} = require('../errors');
+
+function findInstance(instanceName, system, commandName) {
+    const instance = system.getInstance(instanceName);
+
+    if (instanceName) {
+        if (!instance) {
+            throw new SystemError(`Ghost instance "${instanceName}" does not exist`);
+        }
+
+        process.chdir(instance.dir);
+    }
+
+    checkValidInstall(commandName);
+
+    return instance;
+}
+
+module.exports = findInstance;

test/unit/utils/get-instance-spec.js

@@ -0,0 +1,59 @@
+'use strict';
+const {expect} = require('chai');
+const sinon = require('sinon');
+const proxyquire = require('proxyquire').noCallThru();
+const {SystemError} = require('../../../lib/errors');
+const modulePath = '../../../lib/utils/get-instance';
+
+describe('Unit: Utils > getInstance', function () {
+    let getInstance, stubs, system;
+    beforeEach(function () {
+        stubs = {
+            checkValidInstall: sinon.stub().callsFake(a => a),
+            chdir: sinon.stub(process, 'chdir'),
+            getInstance: sinon.stub().returns('It\'s-a Me, Mario!')
+        };
+
+        system = {getInstance: stubs.getInstance};
+        getInstance = proxyquire(modulePath, {
+            './check-valid-install': stubs.checkValidInstall
+        });
+    });
+
+    this.afterEach(function () {
+        sinon.restore();
+    });
+
+    it('Doesn\'t change directory by default', function () {
+        const result = getInstance(undefined, system, 'test');
+
+        expect(result).to.equal('It\'s-a Me, Mario!');
+        expect(stubs.getInstance.calledOnce).to.be.true;
+        expect(stubs.chdir.called).to.be.false;
+        expect(stubs.checkValidInstall.calledOnce).to.be.true;
+        expect(stubs.checkValidInstall.calledWithExactly('test')).to.be.true;
+    });
+
+    it('Fails if the instance cannot be found', function () {
+        stubs.getInstance.returns(null);
+
+        try {
+            getInstance('ghosted', system, 'test');
+            expect(false, 'Promise should have rejected').to.be.true;
+        } catch (error) {
+            expect(error).to.be.instanceof(SystemError);
+            expect(error.message).to.equal('Ghost instance "ghosted" does not exist');
+        }
+    });
+
+    it('Chdirs into instance directory when it exists', function () {
+        const dir = '/path/to/ghost';
+        stubs.getInstance.returns({dir});
+
+        const result = getInstance('i', system, 'test');
+
+        expect(result.dir).to.equal(dir);
+        expect(stubs.chdir.calledOnce).to.to.true;
+        expect(stubs.chdir.calledWithExactly(dir)).to.be.true;
+    });
+})