test: tests and updated documentation for recursive dns (#455)

* test: tests for recursive dns

* docs: update documentation for ipfs.dns

Author: niinpatel

SPEC/MISCELLANEOUS.md

@@ -59,9 +59,14 @@ A great source of [examples](https://github.com/ipfs/interface-ipfs-core/blob/ma
 
 > Resolve DNS links
 
-##### `ipfs.dns(domain, [callback])`
+##### `ipfs.dns(domain, [options], [callback])`
 
-`callback` must follow `function (err, path) {}` signature, where `err` is an error if the operation was not successful. `path` is the IPFS path for that domain.
+Where:
+
+- `options` is an optional object argument that might include the following properties:
+    - `recursive` (boolean, default true): resolve until result is not a domain name
+
+- `callback` must follow `function (err, path) {}` signature, where `err` is an error if the operation was not successful. `path` is the IPFS path for that domain.
 
 If no `callback` is passed, a promise is returned.
 

src/miscellaneous/dns.js

@@ -40,5 +40,28 @@ module.exports = (createCommon, options) => {
         done()
       })
     })
+
+    // skipping because there is an error in https://ipfs.io/api/v0/dns?arg=ipfs.io
+    // unskip when it is resolved and the new version released: https://github.com/ipfs/go-ipfs/issues/6086
+    it.skip('should non-recursively resolve ipfs.io', () => {
+      return ipfs.dns('ipfs.io', { recursive: false }).then(res => {
+      // matches pattern /ipns/<ipnsaddress>
+        expect(res).to.match(/\/ipns\/.+$/)
+      })
+    })
+
+    it('should recursively resolve ipfs.io', () => {
+      return ipfs.dns('ipfs.io', { recursive: true }).then(res => {
+      // matches pattern /ipfs/<hash>
+        expect(res).to.match(/\/ipfs\/.+$/)
+      })
+    })
+
+    it('should resolve subdomain docs.ipfs.io', () => {
+      return ipfs.dns('docs.ipfs.io').then(res => {
+      // matches pattern /ipfs/<hash>
+        expect(res).to.match(/\/ipfs\/.+$/)
+      })
+    })
   })
 }