Fix test for extends not at top level and ensure second extends alway…

…s triggers an early exception (#2791)

packages/pug-linker/index.js

@@ -13,10 +13,10 @@ function link(ast) {
   var extendsNode = null;
   if (ast.nodes.length) {
     var hasExtends = ast.nodes[0].type === 'Extends';
+    checkExtendPosition(ast, hasExtends);
     if (hasExtends) {
       extendsNode = ast.nodes.shift();
     }
-    checkExtendPosition(ast, hasExtends);
   }
   ast = applyIncludes(ast);
   ast.declaredBlocks = findDeclaredBlocks(ast);
@@ -164,7 +164,7 @@ function checkExtendPosition(ast, hasExtends) {
       if (hasExtends && !legitExtendsReached) {
         legitExtendsReached = true;
       } else {
-        error('EXTENDS_NOT_FIRST', 'Declaration of template inheritance ("extends") should be the first thing in the file.', node);
+        error('EXTENDS_NOT_FIRST', 'Declaration of template inheritance ("extends") should be the first thing in the file. There can only be one extends statement per file.', node);
       }
     }
   });

packages/pug-linker/test/__snapshots__/index.test.js.snap

@@ -3570,7 +3570,7 @@ exports[`error handling extends-not-first.input.json 1`] = `
 Object {
   "code": "PUG:EXTENDS_NOT_FIRST",
   "line": 4,
-  "msg": "Declaration of template inheritance (\"extends\") should be the first thing in the file.",
+  "msg": "Declaration of template inheritance (\"extends\") should be the first thing in the file. There can only be one extends statement per file.",
 }
 `;
 

packages/pug/test/extends-not-top-level/duplicate.pug

@@ -0,0 +1,2 @@
+extends default
+extends default

packages/pug/test/extends-not-top-level/index.test.js

@@ -0,0 +1,19 @@
+const pug = require('../../');
+
+// regression test for #2404
+
+test('extends not top level should throw an error', () => {
+  expect(
+    () => pug.compileFile(
+      __dirname + '/index.pug'
+    )
+  ).toThrow('Declaration of template inheritance ("extends") should be the first thing in the file. There can only be one extends statement per file.');
+});
+
+test('duplicate extends should throw an error', () => {
+  expect(
+    () => pug.compileFile(
+      __dirname + '/duplicate.pug'
+    )
+  ).toThrow('Declaration of template inheritance ("extends") should be the first thing in the file. There can only be one extends statement per file.');
+});

packages/pug/test/pug.test.js

@@ -890,15 +890,6 @@ describe('pug', function(){
     it('does not produce warnings for issue-1593', function () {
       pug.compileFile(__dirname + '/fixtures/issue-1593/index.pug');
     });
-    it('does throw error for issue-2404', function () {
-      var message = '';
-      try {
-        pug.compileFile(__dirname + '/fixtures/issue-2404/mixin.call.extends.pug');
-      } catch (e) {
-        message = e.message;
-      }
-      assert(message.indexOf('Declaration of template inheritance ("extends") should be the first thing in the file.') !== -1);
-    });
     it('should support caching (pass 1)', function () {
       fs.writeFileSync(__dirname + '/temp/input-compileFile.pug', '.foo bar');
       var fn = pug.compileFile(__dirname + '/temp/input-compileFile.pug',