Fail when attempting to start an H2 server without SSL context and h2c disabled

Author: DerGuteMoritz

src/aleph/http/server.clj

@@ -732,6 +732,7 @@
            http-versions
            ssl-context
            manual-ssl?
+           use-h2c?
            shutdown-executor?
            epoll?
            transport
@@ -757,6 +758,12 @@
                                   :ssl? (or manual-ssl? (boolean ssl-context))
                                   :http1-pipeline-transform http1-pipeline-transform
                                   :continue-executor continue-executor))]
+
+    (when (and (not ssl-context)
+               (not use-h2c?)
+               (some #{:http2} http-versions))
+      (throw (IllegalArgumentException. "HTTP/2 requires ssl-context to be given or use-h2c? to be true.")))
+
     (netty/start-server
       {:pipeline-builder    pipeline-builder
        :bootstrap-transform bootstrap-transform

test/aleph/http_test.clj

@@ -1403,8 +1403,8 @@
   (testing "HTTP/2 without ssl-context"
     (let [result (try-start-server
                   {:http-versions [:http2]})]
-      ;; TODO: Shouldn't this fail?
-      (is (= :started result))))
+      (is (instance? IllegalArgumentException result))
+      (is (= "HTTP/2 requires ssl-context to be given or use-h2c? to be true." (ex-message result)))))
   (testing "HTTP/2 without ssl-context but with h2c"
     (let [result (try-start-server
                   {:use-h2c? true