Add some tests that were laying around

unittests/array_access.chai

@@ -0,0 +1,3 @@
+var v = [[[15]]]
+
+assert_true(v[0][0][0] == 15)

unittests/instring_eval_with_string.chai

@@ -0,0 +1 @@
+assert_equal("a string", "${"a string"}")

unittests/return_value_assignment.chai

@@ -0,0 +1,16 @@
+
+try {
+  eval("to_string(5) = \"some string\"")
+  assert_true(false)
+} catch (e) {
+  print("Caught Error: " + e.what());
+}
+
+
+
+try {
+  eval("var v = [1,2,3]; v.size() = 3")
+  assert_true(false)
+} catch (e) {
+  print("Caught Error: " + e.what());
+}