Ensure meditations expressions alternate properly

Hat tip to @SeriousPony for the report

Author: trptcolin

.gitignore

@@ -28,4 +28,5 @@ syntax: glob
 .cake/
 .lein-failures
 .lein-deps-sum
+.lein-repl-history
 autodoc/**

src/koan_engine/core.clj

@@ -4,8 +4,16 @@
 (def __ :fill-in-the-blank)
 (def ___ (fn [& args] __))
 
+(defn ensure-valid-meditation [doc-expression-pairs]
+  (doseq [[doc expression] doc-expression-pairs]
+    (when-not (string? doc)
+      (throw (ex-info (str "Meditations must be alternating doc/expression pairs\n"
+                           "Expected " doc " to be a documentation string")
+                      {:line (:line (meta doc))}))))
+  doc-expression-pairs)
+
 (defmacro meditations [& forms]
-  (let [pairs (partition 2 forms)
+  (let [pairs (ensure-valid-meditation (partition 2 forms))
         tests (map (fn [[doc# code#]]
                      `(u/fancy-assert ~code# ~doc#))
                    pairs)]

src/koan_engine/koans.clj

@@ -21,27 +21,28 @@
         (first more)
         (recur more)))))
 
+(defn report-error [file-path line error]
+  (let [message (or (.getMessage error) (.toString error))]
+    (println "\nNow meditate upon"
+             (str file-path
+                  (when line (str ":" line))))
+    (println "---------------------")
+    (println "Assertion failed!")
+    (println (.replaceFirst message "^Assert failed: " ""))))
+
 (defn tests-pass? [dojo-path file-path]
   (u/with-dojo [dojo-path]
     (print "Considering" (str file-path "..."))
     (println)
     (flush)
     (try (load-file file-path)
          true
+         (catch clojure.lang.ExceptionInfo ei
+           (report-error file-path (:line (ex-data ei)) ei)
+           false)
          (catch Throwable e
-           (let [message (or (.getMessage e) (.toString e))
-                 ; TODO: use ex-info or something to clean this up
-                 line (when-let [groups (first (re-seq #"^\[LINE (\d+)\] "
-                                                       message))]
-                        (last groups))]
-             (println "\nNow meditate upon"
-                      (str file-path
-                           (when line (str ":" line))))
-             (println "---------------------")
-             (println "Assertion failed!")
-             (println (.replaceFirst
-                        (.replaceFirst message "^Assert failed: " "")
-                        "^\\[LINE \\d+\\] " "")))
+
+             (report-error file-path nil e)
            false))))
 
 (defn namaste []

src/koan_engine/util.clj

@@ -35,9 +35,8 @@
   ([x message]
      `(try (safe-assert ~x ~message)
            (catch Throwable e#
-             (throw (Exception. (str ~(when-let [line (:line (meta x))]
-                                        (str "[LINE " line "] "))
-                                     '~message "\n" '~x)))))))
+             (throw (ex-info (str '~message "\n" '~x)
+                             {:line (:line (meta '~x))}))))))
 
 (defn read-project []
   (let [rdr (clojure.lang.LineNumberingPushbackReader.