increase test coverage on ast helper

Author: ichiriac

src/ast.js

@@ -356,9 +356,6 @@ AST.prototype.prepare = function(kind, docs, parser) {
     let location = null;
     const args = Array.prototype.slice.call(arguments);
     args.push(docs);
-    if (typeof result.preBuild === "function") {
-      result.preBuild(arguments);
-    }
     if (self.withPositions || self.withSource) {
       let src = null;
       if (self.withSource) {

test/ast.test.js

@@ -0,0 +1,27 @@
+const parser = require("./main");
+
+describe("Test AST class (edge cases)", function() {
+    it("test source without location", function() {
+        const test = parser.create({
+            ast: {
+                withPositions: false,
+                withSource: true
+            }
+        });
+        const ast = test.parseEval('echo $foo;');
+        const echo = ast.children[0];
+        expect(echo.loc.source).toBe("echo $foo;");
+        expect(echo.loc.start).toBeNull();
+        expect(echo.loc.end).toBeNull();
+
+        const variable = echo.expressions[0];
+        expect(variable.loc.source).toBe("$foo");
+    });
+    it("test undefined node", function() {
+        const test = parser.create();
+        expect(() => {
+            const node = test.parser.node('foo');
+            node();
+        }).toThrow(/foo/);
+    });    
+});