Add test for didYouMean with sub-message (#1988)

Author: Cito

src/jsutils/__tests__/didYouMean-test.js

@@ -9,15 +9,15 @@ describe('didYouMean', () => {
     expect(didYouMean([])).to.equal('');
   });
 
-  it('Handle single suggestion', () => {
+  it('Handles single suggestion', () => {
     expect(didYouMean(['A'])).to.equal(' Did you mean A?');
   });
 
-  it('Handle two suggestions', () => {
+  it('Handles two suggestions', () => {
     expect(didYouMean(['A', 'B'])).to.equal(' Did you mean A or B?');
   });
 
-  it('Handle multiple suggestions', () => {
+  it('Handles multiple suggestions', () => {
     expect(didYouMean(['A', 'B', 'C'])).to.equal(' Did you mean A, B, or C?');
   });
 
@@ -26,4 +26,10 @@ describe('didYouMean', () => {
       ' Did you mean A, B, C, D, or E?',
     );
   });
+
+  it('Adds sub-message', () => {
+    expect(didYouMean('the letter', ['A'])).to.equal(
+      ' Did you mean the letter A?',
+    );
+  });
 });