Fix #91: decode-body passes a nil body through

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Babashka [http-client](https://github.com/babashka/http-client): HTTP client for Clojure and babashka built on java.net.http
 
+## Unreleased
+
+- [#91](https://github.com/babashka/http-client/issues/91): `decode-body` passes a nil body through, e.g. of a 407 to `CONNECT`
+
 ## 0.4.25 (2026-09-11)
 
 - [#86](https://github.com/babashka/http-client/issues/86): `uri-with-query` no longer decodes the existing query, fragment and user info when `:query-params` are used ([@dylanpulver](https://github.com/dylanpulver))

src/babashka/http_client/interceptors.clj

@@ -211,7 +211,7 @@
    :response (fn [resp]
                (let [as (or (-> resp :request :as) :string)
                      body (:body resp)
-                     body (if (not (string? body))
+                     body (if-not (or (nil? body) (string? body))
                             (case as
                               :string (slurp body)
                               :stream body

test/babashka/http_client_test.clj

@@ -549,6 +549,27 @@
     (is (thrown-with-msg? clojure.lang.ExceptionInfo #":host and :port"
                           (http/->ProxySelector {:host "127.0.0.1"})))))
 
+(deftest proxy-connect-407-test
+  (let [server (java.net.ServerSocket. 0)
+        port (.getLocalPort server)]
+    (future (try (loop []
+                   (with-open [socket (.accept server)]
+                     (let [r (io/reader (.getInputStream socket))
+                           out (io/writer (.getOutputStream socket))]
+                       (dorun (take-while seq (repeatedly #(.readLine r))))
+                       (.write out "HTTP/1.1 407 Proxy Authentication Required\r\nProxy-Authenticate: Basic realm=\"x\"\r\nContent-Length: 0\r\n\r\n")
+                       (.flush out)))
+                   (recur))
+                 (catch Exception _ nil)))
+    (try
+      (let [client (http/client {:proxy {:host "127.0.0.1" :port port}})]
+        (doseq [as [:string :bytes :stream]]
+          (testing (str "a 407 to CONNECT returns status 407 and a nil body with :as " as)
+            (let [resp (http/get "https://example.invalid/" {:client client :throw false :as as})]
+              (is (= 407 (:status resp)))
+              (is (nil? (:body resp)))))))
+      (finally (.close server)))))
+
 (deftest cookie-handler-test
   (testing "nil passthrough"
     (is (nil? (http/->CookieHandler nil))))