viml/parser/expressions,tests: Add AST freeing, with sanity checks

test/helpers.lua

@@ -358,6 +358,8 @@ format_luav = function(v, indent)
     else
       ret = ('%e'):format(v)
     end
+  elseif type(v) == 'nil' then
+    ret = 'nil'
   else
     print(type(v))
     -- Not implemented yet

test/symbolic/klee/viml_expressions_parser.c

@@ -92,6 +92,6 @@ int main(const int argc, const char *const *const argv,
   assert(ast.root != NULL
          || plines[0].size == 0);
   assert(ast.root != NULL || ast.err.msg);
-  // FIXME: check for AST recursiveness
-  // FIXME: free memory and assert no memory leaks
+  viml_pexpr_free_ast(ast);
+  assert(allocated_memory == 0);
 }

test/unit/viml/expressions/parser_spec.lua

@@ -253,6 +253,7 @@ describe('Expressions parser', function()
       end
       eq(exp_highlighting, hls)
     end
+    lib.viml_pexpr_free_ast(east)
   end
   local function hl(group, str, shift)
     return function(next_col)