diff --git a/src/Data.hrl b/include/Data.hrl
similarity index 100%
rename from src/Data.hrl
rename to include/Data.hrl
diff --git a/src/Debug.hrl b/include/Debug.hrl
similarity index 100%
rename from src/Debug.hrl
rename to include/Debug.hrl
diff --git a/src/Shapes.hrl b/include/Shapes.hrl
similarity index 100%
rename from src/Shapes.hrl
rename to include/Shapes.hrl
diff --git a/src/Trees.hrl b/include/Trees.hrl
similarity index 100%
rename from src/Trees.hrl
rename to include/Trees.hrl
diff --git a/src/trees_test.erl b/src/trees_test.erl
deleted file mode 100644
index e4de832..0000000
--- a/src/trees_test.erl
+++ /dev/null
@@ -1,74 +0,0 @@
-%
-% F.Cesarini & S.Thomson, Erlang Programming, p.169.
-% Exercise 7-5: Binary Trees
-%
--module(trees_test).
--export([test/0]).
--include("Trees.hrl").
-
-test() ->
-    sum_undefined_tree(),
-    sum_balanced_tree(),
-    sum_lined_tree(),
-    max_undefined_tree(),
-    max_balanced_tree(),
-    max_lined_tree(),
-    is_ordered_undefined_tree(),
-    is_ordered_false(),
-    is_ordered_true(),
-    insert_into_undefined(),
-    insert_into_left_tree(),
-    insert_equal_into_right_tree(),
-    insert_greater_into_right_tree(),
-    ok.
-
-sum_undefined_tree() ->
-    0 = trees:sum(undefined).
-
-sum_balanced_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
-    20 = trees:sum(Tree).
-
-sum_lined_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 6, left = #bintree{value = 9}}},
-    20 = trees:sum(Tree).
-
-max_undefined_tree() ->
-    0 = trees:max(undefined).
-
-max_balanced_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
-    9 = trees:max(Tree).
-
-max_lined_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 6, left = #bintree{value = 9}}},
-    9 = trees:max(Tree).
-
-is_ordered_undefined_tree() ->
-    true = trees:is_ordered(undefined).
-
-is_ordered_false() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
-    false = trees:is_ordered(Tree).
-
-is_ordered_true() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
-    true = trees:is_ordered(Tree).
-
-insert_into_undefined() ->
-    #bintree{value = 5} = trees:insert(5, undefined).
-
-insert_into_left_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
-    #bintree{value = 5, left = #bintree{value = 4, left = #bintree{value = 3}}, right = #bintree{value = 6}} =
-        trees:insert(3, Tree).
-
-insert_equal_into_right_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
-    #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6, left = #bintree{value = 5}}} =
-        trees:insert(5, Tree).
-
-insert_greater_into_right_tree() ->
-    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
-    #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6, right = #bintree{value = 7}}} =
-        trees:insert(7, Tree).
diff --git a/src/ets_tests.erl b/test/ets_tests.erl
similarity index 100%
rename from src/ets_tests.erl
rename to test/ets_tests.erl
diff --git a/src/recursion_tests.erl b/test/recursion_tests.erl
similarity index 100%
rename from src/recursion_tests.erl
rename to test/recursion_tests.erl
diff --git a/src/regex_tests.erl b/test/regex_tests.erl
similarity index 100%
rename from src/regex_tests.erl
rename to test/regex_tests.erl
diff --git a/test/trees_test.erl b/test/trees_test.erl
new file mode 100644
index 0000000..ba86621
--- /dev/null
+++ b/test/trees_test.erl
@@ -0,0 +1,58 @@
+%
+% F.Cesarini & S.Thomson, Erlang Programming, p.169.
+% Exercise 7-5: Binary Trees
+%
+-module(trees_test).
+-include("Trees.hrl").
+-include_lib("eunit/include/eunit.hrl").
+
+sum_undefined_tree_test() ->
+    ?assertEqual(0, trees:sum(undefined)).
+
+sum_balanced_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
+    ?assertEqual(20, trees:sum(Tree)).
+
+sum_lined_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 6, left = #bintree{value = 9}}},
+    ?assertEqual(20, trees:sum(Tree)).
+
+max_undefined_tree_test() ->
+    ?assertEqual(0, trees:max(undefined)).
+
+max_balanced_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
+    ?assertEqual(9, trees:max(Tree)).
+
+max_lined_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 6, left = #bintree{value = 9}}},
+    ?assertEqual(9, trees:max(Tree)).
+
+is_ordered_undefined_tree_test() ->
+    ?assert(trees:is_ordered(undefined)).
+
+is_ordered_false_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 6}, right = #bintree{value = 9}},
+    ?assertNot(trees:is_ordered(Tree)).
+
+is_ordered_true_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
+    ?assert(trees:is_ordered(Tree)).
+
+insert_into_undefined_test() ->
+    ?assertEqual(#bintree{value = 5}, trees:insert(5, undefined)).
+
+insert_into_left_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
+    ?assertEqual(#bintree{value = 5, left = #bintree{value = 4, left = #bintree{value = 3}}, right = #bintree{value = 6}},
+        trees:insert(3, Tree)).
+
+insert_equal_into_right_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
+    ?assertEqual(#bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6, left = #bintree{value = 5}}},
+        trees:insert(5, Tree)).
+
+insert_greater_into_right_tree_test() ->
+    Tree = #bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6}},
+    ?assertEqual(#bintree{value = 5, left = #bintree{value = 4}, right = #bintree{value = 6, right = #bintree{value = 7}}},
+        trees:insert(7, Tree)).