Start the function only once in test

If a test using `WithFunction` contains multiple test method, the function will be started multiple time, wich will fail the test.

Using an atomic boolean to be sure that the function is only started once fixes the issue.

Fixes #44661

Author: loicmathieu

integration-tests/google-cloud-functions/src/test/java/io/quarkus/gcp/function/test/HttpFunctionTestCase.java

@@ -21,4 +21,15 @@ public void test() {
                 .statusCode(200)
                 .body(is("Hello World!"));
     }
+
+    // we do twice the test to be sure we can call multiple time the same function
+    @Test
+    public void test2() {
+        // test the function using RestAssured
+        when()
+                .get()
+                .then()
+                .statusCode(200)
+                .body(is("Hello World!"));
+    }
 }

test-framework/google-cloud-functions/src/main/java/io/quarkus/google/cloud/functions/test/CloudFunctionTestResource.java

@@ -2,6 +2,7 @@
 
 import java.util.Collections;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.eclipse.microprofile.config.ConfigProvider;
 
@@ -16,6 +17,7 @@ public class CloudFunctionTestResource implements QuarkusTestResourceConfigurabl
     private FunctionType functionType;
     private String functionName;
     private CloudFunctionsInvoker invoker;
+    private final AtomicBoolean started = new AtomicBoolean(false);
 
     @Override
     public void init(WithFunction withFunction) {
@@ -30,14 +32,16 @@ public Map<String, String> start() {
 
     @Override
     public void inject(TestInjector testInjector) {
-        // This is a hack, we cannot start the invoker in the start() method as Quarkus is not yet initialized,
-        // so we start it here as this method is called later (the same for reading the test port).
-        int port = ConfigProvider.getConfig().getOptionalValue("quarkus.http.test-port", Integer.class).orElse(8081);
-        this.invoker = new CloudFunctionsInvoker(functionType, port);
-        try {
-            this.invoker.start();
-        } catch (Exception e) {
-            throw new RuntimeException(e);
+        if (started.compareAndSet(false, true)) {
+            // This is a hack, we cannot start the invoker in the start() method as Quarkus is not yet initialized,
+            // so we start it here as this method is called later (the same for reading the test port).
+            int port = ConfigProvider.getConfig().getOptionalValue("quarkus.http.test-port", Integer.class).orElse(8081);
+            this.invoker = new CloudFunctionsInvoker(functionType, port);
+            try {
+                this.invoker.start();
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
         }
     }