test: test isFullWidthCodePoint with invalid input

Code coverage information shows that we are only testing the happy path for the internal readline `isFullWidthCodePoint()` function. Test it with invalid input. PR-URL: #7422 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Brian White <[email protected]> Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: Trott

test/parallel/test-readline-interface.js

@@ -304,6 +304,11 @@ function isWarned(emitter){
 rli.close();
 }
 
+// isFullWidthCodePoint() should return false for non-numeric values
+[true,false,null,undefined,{},[],'あ'].forEach((v)=>{
+assert.strictEqual(readline.isFullWidthCodePoint('あ'),false);
+});
+
 // wide characters should be treated as two columns.
 assert.equal(readline.isFullWidthCodePoint('a'.charCodeAt(0)),false);
 assert.equal(readline.isFullWidthCodePoint('あ'.charCodeAt(0)),true);