fix(fastly): Return undefined for dict values of write-only edge dicts

Getting the value of an edge dictionary value for a write-only dictionary results in an error 400
from the Fastly API, which is correct, but not helpful. Because `readDictItem` always gets the
dictionary metadata before reading, we can guard against this error and return a proper response
(status: 403, item_value: undefined)

fixes #27

src/index.js

@@ -698,7 +698,23 @@ class Fastly {
     return this.readDictionary(
       await this.getVersion(version, 'latest'),
       name,
-    ).then(({ data }) => this.request.get(`/service/${this.service_id}/dictionary/${data.id}/item/${key}`));
+    ).then(({ data }) => {
+      if (data.write_only) {
+        return {
+          status: 403, // not permitted to read from write-only dicts
+          data: {
+            dictionary_id: data.id,
+            service_id: this.service_id,
+            item_key: key,
+            item_value: undefined,
+            created_at: undefined,
+            deleted_at: undefined,
+            updated_at: undefined,
+          },
+        };
+      }
+      return this.request.get(`/service/${this.service_id}/dictionary/${data.id}/item/${key}`);
+    });
   }
 
   /**

test/readDictItem.test.js

@@ -0,0 +1,56 @@
+'use strict';
+
+/* eslint-env mocha */
+
+const nock = require('nock');
+const expect = require('expect');
+const config = require('../src/config');
+const fastlyPromises = require('../src/index');
+const response = require('./response/dictitem.response');
+
+describe('#readDictItem', () => {
+  const fastly = fastlyPromises('923b6bd5266a7f932e41962755bd4254', 'SU1Z0isxPaozGVKXdv0eY');
+  let res;
+
+  nock(config.mainEntryPoint)
+    // get the dictionary first
+    .get('/service/SU1Z0isxPaozGVKXdv0eY/version/1/dictionary/my_dictionary')
+    .reply(200, response.dict.get)
+    // list
+    .get('/service/SU1Z0isxPaozGVKXdv0eY/dictionary/5clCytcTJrnvPi8wjqPH0q/item/some_key')
+    .reply(200, response.item.get);
+
+  before(async () => {
+    res = await fastly.readDictItem(1, 'my_dictionary', 'some_key');
+  });
+
+  it('response should be a status 200', () => {
+    expect(res.status).toBe(200);
+  });
+
+  it('response body should exist', () => {
+    expect(res.data).toBeTruthy();
+  });
+
+  it('response body should be an object', () => {
+    expect(typeof res.data).toBe('object');
+  });
+
+  it('response value should match', () => {
+    expect(res.data.item_value).toBe('some_value');
+  });
+
+  it('response body should contain all properties', () => {
+    [
+      'dictionary_id',
+      'service_id',
+      'item_key',
+      'item_value',
+      'created_at',
+      'deleted_at',
+      'updated_at',
+    ].forEach((e) => {
+      expect(Object.keys(res.data)).toContain(e);
+    });
+  });
+});

test/readDictItem.writeonly.js

@@ -0,0 +1,56 @@
+'use strict';
+
+/* eslint-env mocha */
+
+const nock = require('nock');
+const expect = require('expect');
+const config = require('../src/config');
+const fastlyPromises = require('../src/index');
+const response = require('./response/dictitem.response');
+
+describe('#readDictItem (write-only)', () => {
+  const fastly = fastlyPromises('923b6bd5266a7f932e41962755bd4254', 'SU1Z0isxPaozGVKXdv0eY');
+  let res;
+
+  nock(config.mainEntryPoint)
+    // get the dictionary first
+    .get('/service/SU1Z0isxPaozGVKXdv0eY/version/1/dictionary/secret_dictionary')
+    .reply(200, response.dict.getsecret);
+
+  before(async () => {
+    res = await fastly.readDictItem(1, 'secret_dictionary', 'some_key');
+  });
+
+  it('response should be a status 200', () => {
+    expect(res.status).toBe(403);
+  });
+
+  it('response body should exist', () => {
+    expect(res.data).toBeTruthy();
+  });
+
+  it('response body should be an object', () => {
+    expect(typeof res.data).toBe('object');
+  });
+
+  it('response value should match', () => {
+    expect(res.data.item_value).toBeUndefined();
+    expect(res.data.created_at).toBeUndefined();
+    expect(res.data.deleted_at).toBeUndefined();
+    expect(res.data.updated_at).toBeUndefined();
+  });
+
+  it('response body should contain all properties', () => {
+    [
+      'dictionary_id',
+      'service_id',
+      'item_key',
+      'item_value',
+      'created_at',
+      'deleted_at',
+      'updated_at',
+    ].forEach((e) => {
+      expect(Object.keys(res.data)).toContain(e);
+    });
+  });
+});

test/response/dictitem.response.js

@@ -22,6 +22,16 @@ module.exports = {
       version: 1,
       write_only: false,
     },
+    getsecret: {
+      created_at: '2016-05-03T16:11:41+00:00',
+      deleted_at: null,
+      id: '5clCytcTJrnvPi8wjqPH0q',
+      name: 'my_dictionary',
+      service_id: 'SU1Z0isxPaozGVKXdv0eY',
+      updated_at: '2016-05-03T16:20:35+00:00',
+      version: 1,
+      write_only: true,
+    },
     post: {
       created_at: '2016-05-03T16:11:41+00:00',
       deleted_at: null,