more PR review

fastify.js

@@ -401,11 +401,11 @@ function fastify (options) {
 
   try {
     const dc = require('diagnostics_channel')
-    const initChannel = dc.channel('fastify.initialized')
+    const initChannel = dc.channel('fastify.initialization')
     if (initChannel.hasSubscribers) {
       initChannel.publish({ fastify })
     }
-  } catch {
+  } catch (e) {
     // This only happens if `diagnostics_channel` isn't available, i.e. earlier
     // versions of Node.js. In that event, we don't care, so ignore the error.
   }

test/diagnostics-channel.test.js

@@ -2,25 +2,60 @@
 
 const t = require('tap')
 const test = t.test
-let dc
-try {
-  dc = require('diagnostics_channel')
-} catch {
-  // Not available in this version of Node.js
-  t.skip('diagnostics_channel is not available')
-  process.exit(0)
-}
-
-test('diagnostics_channel', t => {
-  t.plan(2)
+const proxyquire = require('proxyquire')
+
+test('diagnostics_channel when present and subscribers', t => {
+  t.plan(3)
 
   let fastifyInHook
 
-  const channel = dc.channel('fastify.initialized')
-  channel.subscribe(function ({ fastify }) {
-    t.pass('message passed to channel')
-    fastifyInHook = fastify
-  })
-  const fastify = require('../fastify')()
+  const dc = {
+    channel (name) {
+      t.equal(name, 'fastify.initialization')
+      return {
+        hasSubscribers: true,
+        publish (event) {
+          t.ok(event.fastify)
+          fastifyInHook = event.fastify
+        }
+      }
+    },
+    '@noCallThru': true
+  }
+
+  const fastify = proxyquire('../fastify', {
+    diagnostics_channel: dc
+  })()
   t.equal(fastifyInHook, fastify)
 })
+
+test('diagnostics_channel when present and no subscribers', t => {
+  t.plan(1)
+
+  const dc = {
+    channel (name) {
+      t.equal(name, 'fastify.initialization')
+      return {
+        hasSubscribers: false,
+        publish () {
+          t.fail('publish should not be called')
+        }
+      }
+    },
+    '@noCallThru': true
+  }
+
+  proxyquire('../fastify', {
+    diagnostics_channel: dc
+  })()
+})
+
+test('diagnostics_channel when not present', t => {
+  t.plan(1)
+
+  t.doesNotThrow(() => {
+    proxyquire('../fastify', {
+      diagnostics_channel: null
+    })()
+  })
+})