[macroexpand] Ensure print mw doesn't interfere with expansion

Author: alexander-yakushev

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master (unreleased)
 
+* [#900](https://github.com/clojure-emacs/cider-nrepl/pull/900): Fix print middleware interfering with macroexpansion.
+
 ## 0.50.1 (2024-08-28)
 
 * Bump `orchard` to [0.27.2](https://github.com/clojure-emacs/orchard/blob/master/CHANGELOG.md#0272-2024-08-28).

src/cider/nrepl/middleware/macroexpand.clj

@@ -153,7 +153,13 @@
                    expander-code (format "(%s '%s)" expander-fn code)
                    transport (eval-interceptor-transport
                               msg macroexpansion-reply-clj :macroexpand-error)]
-               (assoc msg :op "eval", :code expander-code, :transport transport))
+               (assoc msg
+                      :op "eval"
+                      :code expander-code
+                      :transport transport
+                      ;; Make sure nrepl.middleware.print or alternatives don't
+                      ;; stringify our value before it gets back to us.
+                      :nrepl.middleware.print/keys []))
              (catch Exception ex
                (send-middleware-error msg ex)
                nil))]

test/clj/cider/nrepl/middleware/macroexpand_test.clj

@@ -1,10 +1,14 @@
 (ns cider.nrepl.middleware.macroexpand-test
   (:refer-clojure :exclude [zero? zipmap])
   (:require
+   [cider.nrepl]
    [cider.nrepl.test-session :as session]
    [clojure.set :as set]
    [clojure.string]
-   [clojure.test :refer :all]))
+   [clojure.test :refer :all]
+   [nrepl.middleware.interruptible-eval]
+   [nrepl.middleware.print]
+   [nrepl.middleware.session]))
 
 (use-fixtures :once session/session-fixture)
 
@@ -166,3 +170,25 @@
                                                        :print-meta "true"})]
       (is (= "(def ^{:arglists (quote ([]))} x (fn ([] nil)))" expansion))
       (is (= #{"done"} status)))))
+
+(deftest print-mw-before-macroexpand-mw-test
+  (testing "if print middleware ends up before macroexpand mw on the way up,
+it doesn't mess up macroexpansion output"
+    ;; Start a custom server
+    (binding [session/*handler* (cider.nrepl/wrap-macroexpand
+                                 (nrepl.middleware.session/session
+                                  (nrepl.middleware.print/wrap-print
+                                   (nrepl.middleware.interruptible-eval/interruptible-eval nil))))]
+      (session/session-fixture
+       (fn []
+         (let [{:keys [expansion status]} (session/message {:op "macroexpand"
+                                                            :expander "macroexpand-1"
+                                                            :code (:expr code)
+                                                            :display-namespaces "none"})]
+           (is (= (:expanded-1 code) expansion)))
+
+         (let [{:keys [expansion status]} (session/message {:op "macroexpand"
+                                                            :expander "macroexpand"
+                                                            :code (:expr code)
+                                                            :display-namespaces "none"})]
+           (is (= (:expanded code) expansion))))))))