{"id":1532,"date":"2022-10-04T12:54:48","date_gmt":"2022-10-04T10:54:48","guid":{"rendered":"https:\/\/www.loicmathieu.fr\/wordpress\/?p=1532"},"modified":"2022-10-04T12:58:40","modified_gmt":"2022-10-04T10:58:40","slug":"tester-une-java-google-cloud-function","status":"publish","type":"post","link":"https:\/\/www.loicmathieu.fr\/wordpress\/informatique\/tester-une-java-google-cloud-function\/","title":{"rendered":"Testing a Java Google Cloud Function"},"content":{"rendered":"

Until recently, testing a Google Cloud Function written in Java could be done via the invoker provided by the Google Cloud Functions SDK but not via a unit test. But this changed recently!<\/p>\n

Let’s take the following HTTP function as an example:<\/p>\n

\npublic class HelloHttpFunction implements HttpFunction { \n    @Override\n    public void service(HttpRequest httpRequest, HttpResponse httpResponse) \n            throws Exception { \n        Writer writer = httpResponse.getWriter();\n        writer.write(\"Hello World\");\n    }\n}\n<\/pre>\n
After packaging the function into an \u00fcber JAR, we can download the Google Cloud function invoker via the following Maven command:<\/p>\n
\nmvn dependency:copy \\\n  -Dartifact='com.google.cloud.functions.invoker:java-function-invoker:1.1.1' \\\n  -DoutputDirectory=.\n<\/pre>\n
Then use it to start the function locally:<\/p>\n
\njava -jar java-function-invoker-1.1.1.jar \\\n  --classpath target\/hello-world.jar \\\n  --target org.example.HelloHttpFunction\n<\/pre>\n
Our function is then testable on port 8080.<\/p>\n
Alas, this is not practical from a continuous integration perspective where we would like to run automated tests via JUnit for example.<\/p>\n
Fortunately, the function invoker is an open source project from Google and yours truly has proposed a PR that allows the use it via automated tests by proposing a stop method<\/a> that was missing.<\/p>\n
Using its latest version, we can add the invoker as a Maven dependency to our project to use it in a unit test<\/p>\n
\n\n    com.google.cloud.functions.invoker\n    java-function-invoker\n    1.1.1\n    test\n\n<\/pre>\n
You can then create JUnit tests, for example, for our HTTP function HelloHttpFunction<\/code> we will have the following test:<\/p>\n
\nclass HttpFunctionTestCase {\n    @Test\n    public void test() throws Exception {\n        \/\/ start the invoker without joining to avoid blocking the thread\n        Invoker invoker = new Invoker(\n                8081,\n                \"org.example.HelloHttpFunction\",\n                \"http\",\n                Thread.currentThread().getContextClassLoader());\n        invoker.startTestServer();\n\n        \/\/ test the function using REST-assured\n        when()\n                .get(\"http:\/\/localhost:8081\")\n                .then()\n                .statusCode(200)\n                .body(is(\"Hello World!\"));\n\n        \/\/ stop the invoker\n        invoker.stopServer();\n    }\n}\n<\/pre>\n
The REST-assured<\/a> framework is used here to make writing HTTP tests easier.<\/em><\/p>\n
The third parameter to pass when instantiating the invoker is the type of function to test, all function types are supported:<\/p>\n