throw an exception on input coercion failures.

Previously, the generated error containers were passed to resolvables in
place of the actual parameter values. This should now be fixed.

Fixes alumbra/alumbra#17.

src/alumbra/claro/coercion.clj

@@ -10,7 +10,12 @@
       (data/error
         (format "could not coerce value to '%s': %s"
                 type-name
-                (pr-str value))))))
+                (pr-str value))
+        {:value     value
+         :type-name type-name
+         :throwable (format "[%s] %s"
+                            (.getName (class t))
+                            (.getMessage t))}))))
 
 (defn- wrap-coercer-exception
   [f type-name]
@@ -52,9 +57,15 @@
 
 (defn coerce-value
   [{:keys [schema scalars]} type-name value]
-  (-> (or (get-in scalars [type-name :decode])
-          (let [{:keys [type->kind]} schema]
-            (if (= (type->kind type-name) :enum)
-              csk/->kebab-case-keyword
-              #(default-coercer type-name %))))
-      (call-coercer type-name value)))
+  (let [result (-> (or (get-in scalars [type-name :decode])
+                       (let [{:keys [type->kind]} schema]
+                         (if (= (type->kind type-name) :enum)
+                           csk/->kebab-case-keyword
+                           #(default-coercer type-name %))))
+                   (call-coercer type-name value))]
+    (if (data/error? result)
+      (throw
+        (ex-info
+          (data/error-message result)
+          (data/error-data result)))
+      result)))

test/alumbra/claro/coercion_test.clj

@@ -3,6 +3,7 @@
              [properties :as prop]
              [generators :as gen]
              [clojure-test :refer [defspec]]]
+            [clojure.test :refer :all]
             [camel-snake-kebab.core :as csk]
             [claro.data :as data]
             [alumbra.claro.fixtures :as fix]))
@@ -173,3 +174,27 @@
                        (execute!)
                        (get-in [:data "result"]))]
         (output-valid? result)))))
+
+(deftest t-input-coercion-exception
+  (let [decode #(throw (ex-info "oops." {:value %}))
+        encode str
+        execute! (fix/execute-fn
+                   {:schema  schema
+                    :query   {:as-id (->Identity nil (constantly true))}
+                    :scalars {"ID" {:encode encode, :decode decode}}})]
+    (is (thrown-with-msg?
+          clojure.lang.ExceptionInfo
+          #"could not coerce value to 'ID'"
+          (execute! "{ asId(v: 10) }")))))
+
+(deftest t-output-coercion-exception
+  (let [decode str
+        encode #(throw (ex-info "oops." {:value %}))
+        execute! (fix/execute-fn
+                   {:schema  schema
+                    :query   {:as-id (->Identity nil (constantly true))}
+                    :scalars {"ID" {:encode encode, :decode decode}}})
+        result (is (execute! "{ asId(v: 10) }"))]
+    (is (= {"asId" nil} (:data result)))
+    (is (= "could not coerce value to 'ID': \"10\""
+           (-> result :errors first :message)))))