URL-encode path parameters for Router.url

The main breaking change from v8.x to v9.x was an upgrade to `path-to-regex`. [That PR](#71) alluded to a breaking change in encoding. Namely, parameters were not URL-encoded: parameters with safe special characters (like spaces) were not percent-encoded, and parameters with special characters that mean something in a URL, such as slashes (path separators) and question marks (query string delimiter).

The motivation for this PR is to make URL-encoding be the default since typically the parameters provided to `Router.url` are plain, unencoded values. Should someone need an escape hatch, they could pass in `{ encode: null }` (I think) to disable the automatic encoding.

Updated tests, docs, and the changelog.

API.md

@@ -382,7 +382,7 @@ router
 <a name="module_koa-router--Router.url"></a>
 
 #### Router.url(path, params) ⇒ <code>String</code>
-Generate URL from url pattern and given `params`.
+Generate URL from the given URL pattern and `params`. This method URL-encodes the parameters before including them in the URL.
 
 **Kind**: static method of <code>[Router](#exp_module_koa-router--Router)</code>  
 

history.md

@@ -1,3 +1,10 @@
+Next
+==================
+
+- [Breaking] URL-encode parameters passed to `Router.url` with `encodeURIComponent`.
+  - Previously, the parameters to insert in a URL were not encoded: `Router.url('/:x', { x: 'hello world' })` produced `"/hello world"` and `Router.url('/:x', { x: 'a/test?param#' })` would throw an error.
+  - Now, all parameters are safely URL-encoded by default: `Router.url('/:x', { x: 'hello world' })` produces `"/hello%20world"` and `Router.url('/:x', { x: 'a/test?param#' })` produces `"/a%2Ftest%3Fparam%23"`.
+
 9.0.0 / 2020-04-09
 ==================
 

lib/layer.js

@@ -118,7 +118,7 @@ Layer.prototype.url = function (params, options) {
     }
   }
 
-  const toPath = compile(url, options);
+  const toPath = compile(url, Object.assign({ encode: encodeURIComponent }, options));
   let replaced;
 
   const tokens = parse(url);

test/lib/layer.js

@@ -239,11 +239,8 @@ describe('Layer', function() {
 
     it('escapes using encodeURIComponent()', function() {
       const route = new Layer('/:category/:title', ['get'], [function () {}], {name: 'books'});
-      const url = route.url(
-        { category: 'programming', title: 'how to node' },
-        { encode: encodeURIComponent }
-      );
-      url.should.equal('/programming/how%20to%20node');
+      const url = route.url({ category: 'programming', title: 'how to node & js/ts' });
+      url.should.equal('/programming/how%20to%20node%20%26%20js%2Fts');
     });
 
     it('setPrefix method checks Layer for path', function () {
@@ -269,4 +266,4 @@ describe('Layer', function() {
       prefix.path.should.equal(false)
     });
   });
-});
+});

test/lib/router.js

@@ -1501,6 +1501,14 @@ describe('Router', function () {
         .url("Picard", "Enterprise")
         .should.Error();
     });
+
+    it('escapes using encodeURIComponent()', function() {
+      const url = Router.url(
+        '/:category/:title',
+        { category: 'programming', title: 'how to node & js/ts' }
+      );
+      url.should.equal('/programming/how%20to%20node%20%26%20js%2Fts');
+    });
   });
 
   describe('Router#param()', function () {