Adds formats() to Document (#2039)

* move format logic, add filter <> format check

* move logic for filter checks

Author: fstanis

lib/Document.js

@@ -79,6 +79,25 @@ module.exports = class Document {
     return '';
   }
 
+  formats() {
+    if (this.metadata.formats) {
+      return this.metadata.formats;
+    }
+
+    if (this.isAmpStory) {
+      return ['stories'];
+    }
+    if (this.isAmpAds) {
+      return ['ads'];
+    }
+    if (this.isAmpEmail) {
+      return ['email'];
+    }
+
+    // Use websites as fallback as isAmpWebsites could be true for all formats
+    return ['websites'];
+  }
+
   /**
    * Returns true if the document contains a canonical link
    */

lib/DocumentParser.js

@@ -246,7 +246,19 @@ class DocumentParser {
     return string.replace('https://cdn.ampproject.org/amp4ads-v0.js', 'https://cdn.ampproject.org/v0.js');
   }
 
+  verifySectionFilters(section) {
+    if (!section || !section.filters) {
+      return;
+    }
+    for (const filter of section.filters) {
+      if (!this.document.formats().includes(filter)) {
+        throw new Error(`Section uses filter that's not listed in formats: ${filter}`);
+      }
+    }
+  }
+
   endSection() {
+    this.verifySectionFilters(this.section);
     this.section = null;
   }
 

spec/compiler/DocumentSpec.js

@@ -80,6 +80,18 @@ describe("Document", function() {
 
   });
 
+  describe("formats", function() {
+    it("is determined automatically ", function() {
+      doc.isAmpEmail = true;
+      expect(doc.formats()).toEqual(['email']);
+    });
+    it("is extracted from metadata", function() {
+      doc.isAmpEmail = true;
+      doc.metadata.formats = ['websites', 'email'];
+      expect(doc.formats()).toEqual(['websites', 'email']);
+    });
+  });
+
   describe("hasCanonical is", function() {
     it("true if head contains canonical link ", function() {
       doc.appendHead(CANONICAL);