test: increase querystring coverage

PR-URL: nodejs/node#12163
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-querystring-escape.js

@@ -9,6 +9,11 @@ assert.deepStrictEqual(qs.escape('test'), 'test');
 assert.deepStrictEqual(qs.escape({}), '%5Bobject%20Object%5D');
 assert.deepStrictEqual(qs.escape([5, 10]), '5%2C10');
 assert.deepStrictEqual(qs.escape('Ŋōđĕ'), '%C5%8A%C5%8D%C4%91%C4%95');
+assert.deepStrictEqual(qs.escape('testŊōđĕ'), 'test%C5%8A%C5%8D%C4%91%C4%95');
+assert.deepStrictEqual(qs.escape(`${String.fromCharCode(0xD800 + 1)}test`),
+                       '%F0%90%91%B4est');
+assert.throws(() => qs.escape(String.fromCharCode(0xD800 + 1)),
+              /^URIError: URI malformed$/);
 
 // using toString for objects
 assert.strictEqual(
@@ -17,9 +22,11 @@ assert.strictEqual(
 );
 
 // toString is not callable, must throw an error
-assert.throws(() => qs.escape({toString: 5}));
+assert.throws(() => qs.escape({toString: 5}),
+              /^TypeError: Cannot convert object to primitive value$/);
 
 // should use valueOf instead of non-callable toString
 assert.strictEqual(qs.escape({toString: 5, valueOf: () => 'test'}), 'test');
 
-assert.throws(() => qs.escape(Symbol('test')));
+assert.throws(() => qs.escape(Symbol('test')),
+              /^TypeError: Cannot convert a Symbol value to a string$/);

test/parallel/test-querystring.js

@@ -308,6 +308,8 @@ function demoDecode(str) {
 }
 check(qs.parse('a=a&b=b&c=c', null, null, { decodeURIComponent: demoDecode }),
       { aa: 'aa', bb: 'bb', cc: 'cc' });
+check(qs.parse('a=a&b=b&c=c', null, '==', { decodeURIComponent: (str) => str }),
+      { 'a=a': '', 'b=b': '', 'c=c': '' });
 
 // Test QueryString.unescape
 function errDecode(str) {