Test diff output breaks when comparing different types of maps

[André Eriksson]

Comparing e.g. PersistentArrayMaps to PersistentHashMaps breaks the diff.

As an example, the following test:

(deftest t (testing (is (= {0 0} {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8}))))

gives the following output:

expected: {0 0}
  actual: {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8}

    diff: - {0 0}
          + {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8}

…while:

(deftest t (testing (is (= {0 0} {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9}))))

gives:

expected: {0 0}
  actual: {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9}

expected: {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9} to be an instance of clojure.lang.PersistentArrayMap
     was: {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9} is an instance of clojure.lang.PersistentArrayMap

(the difference here being that map literals are interpreted as either hash maps or array maps depending on the number of elements)