The Key Selenium Interview Questions that Matter the Most

# Docker Compose for test environment
version: '3.8'
services:
  selenium-hub:
    image: selenium/hub:4.15.0
    container_name: selenium-hub
    ports:
      - "4444:4444"
    environment:
      - GRID_MAX_SESSION=16
      - GRID_BROWSER_TIMEOUT=300
      - GRID_TIMEOUT=300
  chrome-node:
    image: selenium/node-chrome:4.15.0
    shm_size: 2gb
    depends_on:
      - selenium-hub
    environment:
      - HUB_HOST=selenium-hub
      - NODE_MAX_INSTANCES=2
      - NODE_MAX_SESSION=2
    scale: 3
  test-app:
    image: test-application:latest
    ports:
      - "8080:8080"
    environment:
      - DATABASE_URL=jdbc:mysql://test-db:3306/testdb
      - REDIS_URL=redis://test-redis:6379
    depends_on:
      - test-db
      - test-redis
  test-db:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: testpass
      MYSQL_DATABASE: testdb
    volumes:
      - ./db-init:/docker-entrypoint-initdb.d

@Configuration
public class TestEnvironmentConfig {
    @Value("${test.environment:staging}")
    private String environment;
    
    @Bean
    public EnvironmentProperties environmentProperties() {
        switch (environment.toLowerCase()) {
            case "dev":
                return EnvironmentProperties.builder()
                    .baseUrl("https://dev.example.com")
                    .databaseUrl("jdbc:mysql://dev-db:3306/testdb")
                    .gridUrl("http://dev-grid:4444")
                    .build();
            case "staging":
                return EnvironmentProperties.builder()
                    .baseUrl("https://staging.example.com")
                    .databaseUrl("jdbc:mysql://staging-db:3306/testdb")
                    .gridUrl("http://staging-grid:4444")
                    .build();
            default:
                throw new IllegalArgumentException("Unknown environment: " + environment);
        }
    }
}

public class EnvironmentProvisioner {
    public TestEnvironment provisionEnvironment(TestSuite testSuite) {
        // Calculate required resources
        int requiredNodes = calculateRequiredNodes(testSuite);
        String environmentId = generateEnvironmentId();
        
        // Provision infrastructure
        KubernetesClient k8sClient = new DefaultKubernetesClient();
        
        // Deploy Selenium Grid
        k8sClient.apps().deployments()
            .inNamespace(environmentId)
            .createOrReplace(createGridDeployment(requiredNodes));
        
        // Deploy application under test
        k8sClient.apps().deployments()
            .inNamespace(environmentId)
            .createOrReplace(createAppDeployment(testSuite.getAppVersion()));
        
        // Wait for readiness
        waitForEnvironmentReady(environmentId);
        
        return new TestEnvironment(environmentId, getEnvironmentUrls(environmentId));
    }
    
    public void cleanupEnvironment(String environmentId) {
        KubernetesClient k8sClient = new DefaultKubernetesClient();
        k8sClient.namespaces().withName(environmentId).delete();
    }
}

public class EnvironmentHealthChecker {
    @Scheduled(fixedRate = 60000) // Check every minute
    public void checkEnvironmentHealth() {
        environmentRegistry.getAllEnvironments().forEach(env -> {
            HealthStatus status = performHealthCheck(env);
            
            if (status.isUnhealthy()) {
                // Attempt automatic recovery
                environmentRecovery.recoverEnvironment(env);
                
                // Alert if recovery fails
                if (!performHealthCheck(env).isHealthy()) {
                    alertManager.sendEnvironmentAlert(env, status);
                }
            }
        });
    }
    
    private HealthStatus performHealthCheck(TestEnvironment env) {
        HealthStatus status = new HealthStatus();
        
        // Check application responsiveness
        status.addCheck("app", checkApplicationHealth(env.getAppUrl()));
        
        // Check Selenium Grid availability
        status.addCheck("grid", checkGridHealth(env.getGridUrl()));
        
        // Check database connectivity
        status.addCheck("database", checkDatabaseHealth(env.getDatabaseUrl()));
        
        return status;
    }
}