test: refactor test-querystring

- change URIError constructor to regular expression in assert.throws
- use block-scope for tests that spans multiple statements

PR-URL: https://github.com/nodejs/node/pull/12661
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Cai <davidcai1993@yahoo.com>

test/parallel/test-querystring.js

@@ -254,7 +254,7 @@ qsWeirdObjects.forEach(function(testCase) {
 // invalid surrogate pair throws URIError
 assert.throws(function() {
   qs.stringify({ foo: '\udc00' });
-}, URIError);
+}, /^URIError: URI malformed$/);
 
 // coerce numbers to string
 assert.strictEqual('foo=0', qs.stringify({ foo: 0 }));
@@ -318,6 +318,7 @@ assert.strictEqual(
     0);
 
 // Test removing limit
+{
   function testUnlimitedKeys() {
     const query = {};
 
@@ -329,9 +330,11 @@ function testUnlimitedKeys() {
       Object.keys(qs.parse(url, null, null, {maxKeys: 0})).length,
       2000);
   }
-testUnlimitedKeys();
 
+  testUnlimitedKeys();
+}
 
+{
   const b = qs.unescapeBuffer('%d3%f2Ug%1f6v%24%5e%98%cb' +
     '%0d%ac%a2%2f%9d%eb%d8%a2%e6');
 // <Buffer d3 f2 55 67 1f 36 76 24 5e 98 cb 0d ac a2 2f 9d eb d8 a2 e6>
@@ -355,6 +358,7 @@ assert.strictEqual(0xeb, b[16]);
   assert.strictEqual(0xd8, b[17]);
   assert.strictEqual(0xa2, b[18]);
   assert.strictEqual(0xe6, b[19]);
+}
 
 assert.strictEqual(qs.unescapeBuffer('a+b', true).toString(), 'a b');
 assert.strictEqual(qs.unescapeBuffer('a+b').toString(), 'a+b');
@@ -368,29 +372,38 @@ assert.strictEqual(qs.unescapeBuffer('a%%').toString(), 'a%%');
 check(qs.parse('%\u0100=%\u0101'), { '%Ā': '%ā' });
 
 // Test custom decode
+{
   function demoDecode(str) {
     return str + 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) {
     throw new Error('To jump to the catch scope');
   }
+
   check(qs.parse('a=a', null, null, {decodeURIComponent: errDecode}),
     {a: 'a'});
+}
 
 // Test custom encode
+{
   function demoEncode(str) {
     return str[0];
   }
+
   const obj = {aa: 'aa', bb: 'bb', cc: 'cc'};
   assert.strictEqual(
     qs.stringify(obj, null, null, {encodeURIComponent: demoEncode}),
     'a=a&b=b&c=c');
+}
 
 // Test QueryString.unescapeBuffer
 qsUnescapeTestCases.forEach(function(testCase) {
@@ -399,12 +412,15 @@ qsUnescapeTestCases.forEach(function(testCase) {
 });
 
 // test overriding .unescape
+{
   const prevUnescape = qs.unescape;
   qs.unescape = function(str) {
     return str.replace(/o/g, '_');
   };
-check(qs.parse('foo=bor'), createWithNoPrototype([{key: 'f__', value: 'b_r'}]));
+  check(
+    qs.parse('foo=bor'),
+    createWithNoPrototype([{key: 'f__', value: 'b_r'}]));
   qs.unescape = prevUnescape;
-
+}
 // test separator and "equals" parsing order
 check(qs.parse('foo&bar', '&', '&'), { foo: '', bar: '' });