Handle reader macros when merging EDN files

.github/workflows/test.yaml

@@ -13,10 +13,10 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses:       actions/checkout@v2
+      uses:       actions/checkout@v4
 
     - name: Cache Maven deps
-      uses: actions/cache@v1
+      uses: actions/cache@v4
       env:
         cache-name: maven-deps
       with:
@@ -46,10 +46,10 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses:       actions/checkout@v2
+      uses:       actions/checkout@v4
 
     - name: Cache Maven deps
-      uses: actions/cache@v1
+      uses: actions/cache@v4
       env:
         cache-name: maven-deps
       with:

src/vessel/resource_merge.clj

@@ -1,8 +1,9 @@
 (ns vessel.resource-merge
   "Support for merging duplicated resources on the classpath."
-  (:require [clojure.java.io :as io]
+  (:require [clojure.edn :as edn]
+            [clojure.java.io :as io]
             [vessel.misc :as misc])
-  (:import (java.io File InputStream)))
+  (:import (java.io File InputStream PushbackReader)))
 
 
 (defn- write-edn
@@ -26,6 +27,14 @@
     :else
     right))
 
+(defn read-edn
+  "Reads an InputStream as EDN but uses a tagged literal for any reader macros found in the stream."
+  [input-stream]
+  (->> input-stream
+       io/reader
+       PushbackReader.
+       (edn/read {:default tagged-literal})))
+
 ;; A rule is a map:
 ;; :match-fn (fn [File]) -> boolean (File is the output file)
 ;; :read-fn (fn [InputStream]) -> value
@@ -42,7 +51,7 @@
 (def edn-base-rule
   "*.edn - deep merged together"
   {:match-fn #(.endsWith (.getPath ^File %) ".edn")
-   :read-fn  misc/read-edn
+   :read-fn  read-edn
    :merge-fn deep-merge
    :write-fn write-edn})
 

test/resources/lib5/with-reader-macros.edn

@@ -0,0 +1,2 @@
+{:k1 :v2
+ :k2 #unknown/macro :v2}

test/resources/lib6/with-reader-macros.edn

@@ -0,0 +1,2 @@
+{:k1 :override-k1
+ :k3 #weird/macro :v3}

test/unit/vessel/builder_test.clj

@@ -90,6 +90,17 @@
       (is (= (.lastModified (io/file src "lib2/resource1.edn"))
              (.lastModified (io/file target "classes/resource1.edn")))))))
 
+(deftest merge-with-reader-macros
+  (let [src    (io/file "test/resources")
+        target (io/file "target/tests/builder-test/reader-macros")
+        _      (builder/copy-files #{(io/file src "lib5")
+                                     (io/file src "lib6")}
+                                   target)]
+
+    (testing "edn files with reader macros are merged"
+      (is (= (slurp (io/file target "classes" "with-reader-macros.edn"))
+             "{:k1 :override-k1, :k2 #unknown/macro :v2, :k3 #weird/macro :v3}")))))
+
 (defn get-file-names
   [^File dir]
   (map #(.getName %) (.listFiles dir)))