Mocking a connection call to AWS DynamoDB in sinon.

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英文:

Mocking a connection call to AWS DynamoDB in sinon

问题

Handler.js 中的 saveUser 方法似乎在测试中仍然尝试连接到 DynamoDB。这可能是因为 db.put 函数返回了一个 Promise 以及在回调中使用了它。您可以尝试将 db.put 函数的 stub 更改为以下形式，以确保它返回一个正确的 Promise：

  1. sandbox.stub(db, "put").callsFake((params, callback) => {
  2.   callback(null, { statusCode: 200 });
  3. });

这将模拟 DynamoDB 的 put 方法并返回一个成功的响应，而不会尝试实际连接到 DynamoDB。这应该解决您的测试问题。

英文:

I have an endpoint in API Gateway which is mapped to a Lambda function in AWS. While writing test cases for the new handler function of the endpoint, I do not want the spec file to call the actual API or connect to DynamoDB. I tried to add a sinon.stub, but it still made the call to connect to DynamoDB and the test-case failed. I am unable to locate where the stub went wrong.

Handler.js:

<!-- begin snippet: js hide: false console: false babel: false -->

<!-- language: lang-js -->

  1. saveUser(userName, logger) {
  2.   const Item = {
  3.     id: uuid.v4(),
  4.     userName,
  5.     ttl: parseInt(Date.now() / 1000) + 900 // expire the name after 15 minutes from now
  6.   };
  7.   const params = {
  8.     TableName: &quot;my-table-name&quot;,
  9.     Item
  10.   };
  11.   logger.log(`Saving new user name to DynamoDB: ${JSON.stringify(params)}`);
  13.   return new Promise(function(resolve, reject) {
  14.     db.put(params, function(err, _) {
  15.       if (err) {
  16.         logger.exception(`Unable to connect to DynamoDB to create: ${err}`);
  17.         reject({
  18.           statusCode: 404,
  19.           err
  20.         });
  21.       } else {
  22.         logger.log(`Saved data to DynamoDB: ${JSON.stringify(Item)}`);
  23.         resolve({
  24.           statusCode: 201,
  25.           body: Item
  26.         });
  27.       }
  28.     });
  29.   });
  30. }

<!-- end snippet -->

Handler.spec.js:

<!-- begin snippet: js hide: false console: false babel: false -->

<!-- language: lang-js -->

  1. import AWS from &quot;aws-sdk&quot;;
  2. const db = new AWS.DynamoDB.DocumentClient({
  3.   apiVersion: &quot;2012-08-10&quot;
  4. });
  6. describe(&quot;user-name-handler&quot;, function() {
  7.   const sandbox = sinon.createSandbox();
  8.   afterEach(() =&gt; sandbox.restore());
  10.   it(&quot;Test saveUser() method&quot;, async function(done) {
  11.     const {
  12.       saveUser
  13.     } = userHandler;
  15.     sandbox.stub(db, &quot;put&quot;)
  16.       .returns(new Promise((resolve, _) =&gt; resolve({
  17.         statusCode: 200
  18.       })));
  20.     try {
  21.       const result = await saveUser(&quot;Sample User&quot;, {
  22.         log: () =&gt; {},
  23.         exception: () =&gt; {}
  24.       });
  26.       expect(result).to.be.equal({
  27.         data: &quot;some data&quot;
  28.       });
  29.       done();
  30.     } catch (err) {
  31.       console.log(err);
  32.       done();
  33.     }
  34.   });
  35. });

<!-- end snippet -->

Error:

  1. Error: Resolution method is overspecified. Specify a callback *or* return a Promise; not both.

I console-logged the err object and it gave me this error, which made me think it is trying to connect to the DynamoDB.

  1. Error: connect ENETUNREACH 127.0.0.1:80
  2.   at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1144:16) {
  3. message: &#39;Missing credentials in config, if using AWS_CONFIG_FILE, set AWS_SDK_LOAD_CONFIG=1&#39;,       
  4. errno: &#39;ENETUNREACH&#39;,
  5. code: &#39;CredentialsError&#39;,
  6. syscall: &#39;connect&#39;,
  7. address: &#39;127.0.0.1&#39;,
  8. port: 80,
  9. time: 2023-05-07T10:45:25.835Z,
  10. originalError: {
  11.   message: &#39;Could not load credentials from any providers&#39;,
  12.   errno: &#39;ENETUNREACH&#39;,
  13.   code: &#39;CredentialsError&#39;,
  14.   syscall: &#39;connect&#39;,
  15.   address: &#39;127.0.0.1&#39;,
  16.   port: 80,
  17.   time: 2023-05-07T10:45:25.835Z,
  18.   originalError: [Object]
  19. }

Related: https://stackoverflow.com/questions/76192814/how-to-test-a-method-which-returns-data-from-aws-dynamodb

答案1

得分: 1

你正在嘲笑测试文件中声明的db，而不是saveUser实际使用的db。

解决方案是将db声明移到它自己的模块中，例如：db.js

  1. const AWS = require("aws-sdk");
  3. const db = new AWS.DynamoDB.DocumentClient({
  4.   apiVersion: "2012-08-10"
  5. });
  7. module.exports = db;

然后从saveUser模块和测试模块都导入它，这样我们将模拟与saveUser使用的相同db实例。

更新：我成功运行了以下代码的测试：

测试代码：

  1. const sinon = require('sinon');
  2. const { saveUser } = require('../userHandler');
  3. const { expect } = require('chai');
  5. const db = require('../db');
  7. describe('user-name-handler', function() {
  8.   afterEach(() => sinon.restore());
  10.   it('Test saveUser() method', async function() {
  12.       sinon.stub(db, 'put')
  13.         .returns(new Promise((resolve, _) => resolve({
  14.             statusCode: 201,
  15.             body: 'some data'
  16.       })));
  18.       try {
  19.           const result = await saveUser(db, 'Sample User', {
  20.             log: () => {},
  21.             exception: () => {}
  22.           });
  24.           expect(result).to.deep.equal({
  25.             statusCode: 201,
  26.             body: 'some data'
  27.           });
  28.       } catch (err) {
  29.         console.log('err', err);
  30.       }
  31.   });
  32. });

userHandler 文件：

  1. const db = require('./db');
  3. const saveUser = (db, userName, logger) => {
  4.   const Item = {
  5.     id: uuid.v4(),
  6.     userName,
  7.     ttl: parseInt(Date.now() / 1000) + 900 // 在当前时间的15分钟后过期名称
  8.   };
  9.   const params = {
  10.     TableName: "my-table-name"
  11.   };
  12.   logger.log(`Saving new user name to DynamoDB: ${JSON.stringify(params)}`);
  14.     return db.put(params, function(err, _) {
  15.       if (err) {
  16.         logger.exception(`Unable to connect to DynamoDB to create: ${err}`);
  17.         return reject({
  18.           statusCode: 404,
  19.           err
  20.         });
  21.       } else {
  22.         logger.log(`Saved data to DynamoDB: ${JSON.stringify(Item)}`);
  23.         return resolve({
  24.           statusCode: 201,
  25.           body: Item
  26.         });
  27.       }
  28.     });
  29. }
  31. module.exports = { saveUser };

这些代码示例中的注释和错误处理需要进一步处理。希望这能帮助你。

英文:

You are mocking the db that is declared in the test file - not the db that saveUser is actually using.

The solution is to move the db declaration to its own module, say: db.js

  1. const AWS = require(&quot;aws-sdk&quot;);
  3. const db = new AWS.DynamoDB.DocumentClient({
  4.   apiVersion: &quot;2012-08-10&quot;
  5. });
  7. module.exports = db;

and then import it both from the module of saveUser and from the test - so that we'll be mocking the same db instance that saveUser uses.

UPDATE

I was able to run the test with the following code successfully:

The test code:

  1. const sinon = require(&#39;sinon&#39;);
  2. const { saveUser } = require(&#39;../userHandler&#39;);
  3. const { expect } = require(&#39;chai&#39;);
  5. const db = require(&#39;../db&#39;);
  7. describe(&#39;user-name-handler&#39;, function() {
  8.   afterEach(() =&gt; sinon.restore());
  10.   it(&#39;Test saveUser() method&#39;, async function() {
  12.       sinon.stub(db, &#39;put&#39;)
  13.         .returns(new Promise((resolve, _) =&gt; resolve({
  14.             statusCode: 201,
  15.             body: &#39;some data&#39;
  16.       })));
  18.       try {
  19.           const result = await saveUser(db, &#39;Sample User&#39;, {
  20.             log: () =&gt; {},
  21.             exception: () =&gt; {}
  22.           });
  24.           expect(result).to.deep.equal({
  25.             statusCode: 201,
  26.             body: &#39;some data&#39;
  27.           });
  28.       } catch (err) {
  29.         console.log(&#39;err&#39;, err);
  30.       }
  31.   });
  32. });

userHandler file:

  1. const db = require(&#39;./db&#39;);
  3. const saveUser = (db, userName, logger) =&gt; {
  4.   const Item = {
  5.     id: uuid.v4(),
  6.     userName,
  7.     ttl: parseInt(Date.now() / 1000) + 900 // expire the name after 15 minutes from now
  8.   };
  9.   const params = {
  10.     TableName: &quot;my-table-name&quot;
  11.   };
  12.   logger.log(`Saving new user name to DynamoDB: ${JSON.stringify(params)}`);
  14.     return db.put(params, function(err, _) {
  15.       if (err) {
  16.         logger.exception(`Unable to connect to DynamoDB to create: ${err}`);
  17.         return reject({
  18.           statusCode: 404,
  19.           err
  20.         });
  21.       } else {
  22.         logger.log(`Saved data to DynamoDB: ${JSON.stringify(Item)}`);
  23.         return resolve({
  24.           statusCode: 201,
  25.           body: Item
  26.         });
  27.       }
  28.     });
  29. }
  31. module.exports = { saveUser };

package.json

  1. {
  2.   &quot;name&quot;: &quot;play&quot;,
  3.   &quot;version&quot;: &quot;1.0.0&quot;,
  4.   &quot;description&quot;: &quot;&quot;,
  5.   &quot;main&quot;: &quot;index.js&quot;,
  6.   &quot;scripts&quot;: {
  7.     &quot;test&quot;: &quot;mocha --timeout 5000&quot;
  8.   },
  9.   &quot;author&quot;: &quot;&quot;,
  10.   &quot;license&quot;: &quot;ISC&quot;,
  11.   &quot;dependencies&quot;: {
  12.     &quot;aws-sdk&quot;: &quot;^2.1373.0&quot;,
  13.     &quot;chai&quot;: &quot;^4.3.7&quot;,
  14.     &quot;mocha&quot;: &quot;^10.2.0&quot;,
  15.     &quot;sinon&quot;: &quot;^15.0.4&quot;
  16.   }
  17. }

OUTPUT
Mocking a connection call to AWS DynamoDB in sinon.

答案2

得分: 0

  1. # 在一个文件中分离DB连接
  2. 我们可以将DB连接分离到一个不同的文件中，并在处理程序实现以及*spec*文件中导入它。
  4. **db.js**
  5. ```js
  6. import AWS from &quot;aws-sdk&quot;;
  7. const db = new AWS.DynamoDB.DocumentClient({ apiVersion: &quot;2012-08-10&quot; });
  9. export default db;

yields() 函数

在存根直接返回Promise的地方，应该与它的回调一起链接一个.yields()。我们可以更改参数以覆盖代码的各个分支。

代码

  1. describe(&quot;user-handler connection success&quot;, function () {
  2.     const sandbox = sinon.createSandbox();
  3.     afterEach(() =&gt; sandbox.restore());
  4.     before(() =&gt; {
  5.         sinon.stub(db, &quot;put&quot;)
  6.             .yields(null, true);
  7.         sinon.stub(db, &quot;get&quot;)
  8.             .yields(null, { sampleKey: &quot;sample value&quot; });
  9.         sinon.stub(db, &quot;delete&quot;)
  10.             .yields(null, { sampleKey: &quot;sample value&quot; });
  11.     });
  12.     after(() =&gt; {
  13.         db.put.restore();
  14.         db.get.restore();
  15.         db.delete.restore();
  16.     });
  18.     it(&quot;Test saveUser() method success&quot;, async function () {
  19.         const result = await userHandler.saveToken(&quot;sample user&quot;, {
  20.             log: () =&gt; {},
  21.             exception: () =&gt; {}
  22.         });
  24.         expect(result.statusCode).to.be.equal(201);
  25.     });
  26. });

有用链接

https://www.youtube.com/watch?v=vXDbmrh0xDQ

  2. <details>
  3. <summary>英文:</summary>
  5. # Separating the DB connection in a file
  6. We can separate the DB connection in a different file and import it in the handler implementation as well as in the *spec* file.
  8. **db.js**
  9. ```js
  10. import AWS from &quot;aws-sdk&quot;;
  11. const db = new AWS.DynamoDB.DocumentClient({ apiVersion: &quot;2012-08-10&quot; });
  13. export default db;

The yields() function

Instead of the stub directly return a Promise, it should be chained with a .yields() along with the parameters its callback will accept. We can change the parameters to cover various branches of the code.

Code

  1. describe(&quot;user-handler connection success&quot;, function () {
  2.     const sandbox = sinon.createSandbox();
  3.     afterEach(() =&gt; sandbox.restore());
  4.     before(() =&gt; {
  5.         sinon.stub(db, &quot;put&quot;)
  6.             .yields(null, true);
  7.         sinon.stub(db, &quot;get&quot;)
  8.             .yields(null, { sampleKey: &quot;sample value&quot; });
  9.         sinon.stub(db, &quot;delete&quot;)
  10.             .yields(null, { sampleKey: &quot;sample value&quot; });
  11.     });
  12.     after(() =&gt; {
  13.         db.put.restore();
  14.         db.get.restore();
  15.         db.delete.restore();
  16.     });
  18.     it(&quot;Test saveUser() method success&quot;, async function () {
  19.         const result = await userHandler.saveToken(&quot;sample user&quot;, {
  20.             log: () =&gt; {},
  21.             exception: () =&gt; {}
  22.         });
  24.         expect(result.statusCode).to.be.equal(201);
  25.     });
  26. });

Useful Link

https://www.youtube.com/watch?v=vXDbmrh0xDQ

huangapple
  • 本文由 发表于 2023年5月7日 20:23:40
  • 转载请务必保留本文链接：https://go.coder-hub.com/76193901.html
  • amazon-dynamodb
  • amazon-web-services
  • aws-api-gateway
  • javascript
  • sinon
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