Split up pretender a bit. It was getting unwieldly.

test/javascripts/helpers/fixture-pretender.js.es6

@@ -0,0 +1,20 @@
+export default function(helpers) {
+  const { response } = helpers;
+  const fixturesByUrl = {};
+
+  // Load any fixtures automatically
+  Ember.keys(require._eak_seen).forEach(entry => {
+    if (/^fixtures/.test(entry)) {
+      const fixture = require(entry, null, null, true);
+      if (fixture && fixture.default) {
+        const obj = fixture.default;
+        Ember.keys(obj).forEach(url => {
+          fixturesByUrl[url] = obj[url];
+          this.get(url, () => response(obj[url]));
+        });
+      }
+    }
+  });
+
+  return fixturesByUrl;
+};