add some more tests

tests/assert.sb

@@ -0,0 +1,6 @@
+def assert(expected, actual) {
+    if expected != actual {
+        print("test failed. expected: ", expected, ", actual: " , actual)
+        exit(1)
+    }
+}

tests/list.sb

@@ -0,0 +1,18 @@
+import assert
+
+as = assert.assert
+
+as([1, 2], [1] + [2])
+as([1, 1], [1] * 2)
+as([1, true, "s", [4], 1, true, "s", [4]], [1, true, "s", [4]] * 2)
+as(1, [1, 2, 3][0])
+as(2, [1, 2, 3][1])
+as(3, [1, 2, 3][2])
+as([1, 2, 3], [1, 2, 3][0:3])
+as([1, 2], [1, 2, 3][0:2])
+as([1], [1, 2, 3][0:1])
+as([], [1, 2, 3][0:0])
+as([2], [1, 2, 3][1:2])
+as([2, 3], [1, 2, 3][1:3])
+
+print("list test succeeded")

tests/str.sb

@@ -0,0 +1,12 @@
+import assert
+
+as = assert.assert
+
+as("ab", "a" + "b")
+as("aaa", "a" * 3)
+as("aaa", 3 * "a")
+as("aaaaaaaaa", 3 * "a" * 3)
+as("a", "abc"[0])
+as("ab", "abc"[0:2])
+
+print("str test succeeded")