Implement sorted flag.

Necessary for Addendum since it is maintaining an unordered list for
each tree node, but `etcd` seems to always produce a sorted listing.

See #29.

addendum.js

@@ -14,6 +14,12 @@ const Reactor = require('reactor')
 
 const Conference = require('conference')
 
+// Comparator function builder.
+const ascension = require('ascension')
+
+// A comparator decorator that extracts values for comparison.
+const whittle = require('whittle')
+
 // An event scheduler to manage multiple timed events inside a calendar using a
 // single `setTimeout`.
 const { Calendar, Timer } = require('happenstance')
@@ -32,6 +38,8 @@ const Log = require('./log')
 
 const AddendumError = require('./error')
 
+const sort = whittle(ascension(String), node => node.key)
+
 // Compassion applications are implemented as a class that implements a specific
 // interface of `async`/`await` functions. Addendum is an implementation of the
 // `etcd` v2 API using Compassion. With it you'll be able to see how you might
@@ -792,6 +800,7 @@ class Addendum {
                     } ]
                 }
             }
+            const sorted = request.query.sorted == 'true' ? listing.sort(sort) : listing
             return {
                 action: 'get',
                 node: {

package.json

@@ -19,6 +19,7 @@
     },
     "dependencies":
     {
+                            "ascension":                    "3.0.0-alpha.12",
                             "compassion":                   "2.0.0-alpha.21",
                             "conference":                   "0.27.0-alpha.3",
                             "cubbyhole":                    "4.0.8",
@@ -27,6 +28,7 @@
                             "fastify-formbody":             "5.1.0",
                             "reactor":                      "17.0.0-alpha.17",
                             "rescue":                       "7.0.0-alpha.18",
+                            "whittle":                      "0.0.5",
                             "wildmap":                      "2.0.0-alpha.1"
     },
     "devDependencies":

test/keys.t.js

@@ -2,7 +2,7 @@
 // **TODO** Does the root key exist on a fresh boot of `etcd` and if so what is
 // its index and value?
 
-const count = 32
+const count = 33
 
 const harness = require('./harness')
 
@@ -135,6 +135,27 @@ async function test (okay, { DELETE, GET, PUT, prune }) {
         }, 'list directory with vivified directory')
     }
 
+    {
+        const response = await GET('/v2/keys/addendum?sorted=true')
+        okay(prune(response), {
+            status: 200,
+            data: {
+                action: 'get',
+                node: {
+                    dir: true,
+                    key: '/addendum',
+                    nodes: [{
+                        key: '/addendum/x',
+                        value: 'y'
+                    }, {
+                        key: '/addendum/y',
+                        dir: true
+                    }]
+                }
+            }
+        }, 'list directory with vivified directory sorted')
+    }
+
     {
         const response = await GET('/v2/keys/addendum?recursive=true')
         okay(prune(response), {