move valid-deps? to specs ns and add explain-deps

src/main/clojure/clojure/tools/deps.clj

@@ -10,7 +10,6 @@
   (:require
     [clojure.java.io :as jio]
     [clojure.set :as set]
-    [clojure.spec.alpha :as s]
     [clojure.string :as str]
     [clojure.tools.deps.util.concurrent :as concurrent]
     [clojure.tools.deps.util.dir :as dir]
@@ -36,9 +35,6 @@
   (let [path (.getAbsolutePath f)]
     (ex-info (format fmt path) {:path path})))
 
-(defn valid-deps? [m]
-  (s/valid? ::specs/deps-map m))
-
 (defn- slurp-edn-map
   "Read the file specified by the path-segments, slurp it, and read it as edn."
   [^File f]
@@ -48,9 +44,9 @@
                    (if (str/starts-with? (.getMessage t) "EOF while reading")
                      (throw (io-err "Error reading edn, delimiter unmatched (%s)" f))
                      (throw (io-err (str "Error reading edn. " (.getMessage t) " (%s)") f)))))]
-    (if (valid-deps? val)
+    (if (specs/valid-deps? val)
       val
-      (throw (io-err "%s is not valid." f)))))
+      (throw (io-err (str "Error reading deps %s. " (specs/explain-deps val)) f)))))
 
 ;; all this canonicalization is deprecated and will eventually be removed
 

src/main/clojure/clojure/tools/deps/specs.clj

@@ -123,6 +123,34 @@
 (s/def :prep/ensure ::path)
 (s/def :prep/fn symbol?)
 
+(defn valid-deps?
+  "Determine whether the deps map is valid according to the specs"
+  [deps-map]
+  (s/valid? ::deps-map deps-map))
+
+(defn explain-deps
+  "If a spec is invalid, return a message explaining why, suitable
+  for an error message"
+  [deps-map]
+  (let [err-data (s/explain-data ::deps-map deps-map)]
+    (if (nil? err-data)
+      "Failed spec, reason unknown"
+      (str "Failed spec, most likely cause:" (System/lineSeparator)
+        (first (clojure.string/split-lines (s/explain-str ::deps-map deps-map)))))))
+
+(defn explain-deps
+  "If a spec is invalid, return a message explaining why, suitable
+  for an error message"
+  [deps-map]
+  (let [err-data (s/explain-data ::deps-map deps-map)]
+    (if (nil? err-data)
+      "Failed spec, reason unknown"
+      (let [problems (->> (::s/problems err-data)
+                       (sort-by #(- (count (:in %))))
+                       (sort-by #(- (count (:path %)))))
+            {:keys [path pred val reason via in]} (first problems)]
+        (str "Found: " (pr-str val) ", expected: " (if reason reason (s/abbrev pred)))))))
+
 ;; API
 
 (s/fdef clojure.tools.deps/resolve-deps
@@ -137,6 +165,7 @@
   :args (s/cat :libs ::lib-map, :paths ::paths, :classpath-args ::classpath-args)
   :ret string?)
 
+
 (comment
   ;; some scratch code to recursively check every deps.edn under
   ;; a root directory whether it's valid against the specs

src/test/clojure/clojure/tools/deps/test_deps.clj

@@ -6,6 +6,7 @@
     [clojure.tools.deps.util :as util]
     [clojure.tools.deps.extensions :as ext]
     [clojure.tools.deps.extensions.faken :as fkn]
+    [clojure.tools.deps.specs :as specs]
     [clojure.tools.deps.util.dir :as dir]
     [clojure.tools.deps.util.maven :as mvn])
   (:import
@@ -297,15 +298,15 @@
 
 (deftest empty-nil-deps-is-valid
   (testing "file exists but is empty (nil)"
-    (is (deps/valid-deps? nil))))
+    (is (specs/valid-deps? nil))))
 
 (deftest TDEPS-238
   (testing "deps are invalid with extra nested vector in :exclusions"
     (let [invalid {:deps
                    {'org.clojure/core.memoize
                     {:mvn/version "1.0.257"
                      :exclusions [['org.clojure/data.priority-map]]}}}]
-      (is (not (deps/valid-deps? invalid))))))
+      (is (not (specs/valid-deps? invalid))))))
 
 (comment
   (test-local-root-relative-to-project-deps)