Use `binary` property on the file object

Backend sends a `binary` property as `false` for some files that
may have a "binary" mime type but are not actually binary. Use that
if it is available before determining if a file is binary or text.

Changelog: fixed

app/assets/javascripts/ide/utils.js

@@ -44,8 +44,8 @@ const KNOWN_TYPES = [
 ];
 
 export function isTextFile({ name, raw, binary, content, mimeType = '' }) {
-  // some file objects already have a `binary` property set on them. If true, return false
-  if (binary) return false;
+  // some file objects already have a `binary` property set on them. If so, use it first
+  if (typeof binary === 'boolean') return !binary;
 
   const knownType = KNOWN_TYPES.find((type) => type.isMatch(mimeType, name));
   if (knownType) return knownType.isText;

spec/frontend/ide/utils_spec.js

@@ -90,6 +90,9 @@ describe('WebIDE utils', () => {
     it('returns true if there is a `binary` property already set on the file object', () => {
       expect(isTextFile({ name: 'abc.txt', content: '' })).toBe(true);
       expect(isTextFile({ name: 'abc.txt', content: '', binary: true })).toBe(false);
+
+      expect(isTextFile({ name: 'abc.tex', content: 'éêė' })).toBe(false);
+      expect(isTextFile({ name: 'abc.tex', content: 'éêė', binary: false })).toBe(true);
     });
   });