Add a test for servletSpec := "3.0"

src/sbt-test/plugins/webapp-components/servlet-3.0/servlet.scala

@@ -0,0 +1,44 @@
+package runners
+
+import com.typesafe.scalalogging.LazyLogging
+import javax.servlet.annotation.WebServlet
+import javax.servlet.http.HttpServlet
+import javax.servlet.http.HttpServletRequest
+import javax.servlet.http.HttpServletResponse
+
+class CountServlet extends HttpServlet with Main:
+
+  import java.sql.Connection
+  import java.sql.DriverManager
+
+  override lazy val c: Connection =
+    Class.forName("org.h2.Driver")
+    val connection: Connection =
+      DriverManager.getConnection("jdbc:h2:mem:", "sa", "")
+    connection.setAutoCommit(false)
+    connection
+
+  override def init(): Unit =
+    super.init()
+
+  override def destroy(): Unit =
+    super.destroy()
+
+  override def doGet(
+      req: HttpServletRequest,
+      res: HttpServletResponse
+  ): Unit =
+    res.addHeader("Content-Type", "application/json")
+    res.getWriter().write(unsafeIncrementAndGetAsJson())
+
+@WebServlet(urlPatterns = Array("/hello"))
+class HelloServlet extends HttpServlet with LazyLogging:
+
+  override def doGet(
+      request: HttpServletRequest,
+      response: HttpServletResponse
+  ): Unit =
+    logger.info("doGet")
+    response.setCharacterEncoding("UTF-8")
+    response.setContentType("text/html")
+    response.getWriter.write("""<h1>Hello, world!</h1>""")

src/sbt-test/plugins/webapp-components/test

@@ -2,3 +2,12 @@
 > reload
 
 > check
+
+$ copy-file servlet-3.0/servlet.scala src/main/scala/04-runners/servlet.scala
+
+# fail to compile with an incompatible Servlet spec
+-> check
+
+# use the correct Servlet spec
+> set servletSpec := "3.0"
+> check