From 748a3adbccfa3e0d5f0a49c63786a594fd528a61 Mon Sep 17 00:00:00 2001
From: Matt Parides <matt.parides@hirefrederick.com>
Date: Mon, 4 Jun 2018 10:43:30 -0700
Subject: [PATCH] added max-length flag to topics tail

---
 commands/topics_tail.js           |  6 +++++-
 test/commands/topics_tail_test.js | 31 ++++++++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/commands/topics_tail.js b/commands/topics_tail.js
index bd6d354..de27137 100644
--- a/commands/topics_tail.js
+++ b/commands/topics_tail.js
@@ -60,7 +60,7 @@ function * tail (context, heroku) {
               cli.log(context.args.TOPIC, partition, m.offset, 0, 'NULL')
               return
             }
-            let length = Math.min(buffer.length, MAX_LENGTH)
+            let length = Math.min(buffer.length, parseInt(context.flags['max-length']) || MAX_LENGTH)
             let body = buffer.toString('utf8', 0, length)
             cli.log(context.args.TOPIC, partition, m.offset, buffer.length, body)
           })
@@ -81,6 +81,9 @@ let cmd = {
     { name: 'TOPIC' },
     { name: 'CLUSTER', optional: true }
   ],
+  flags: [
+    { name: 'max-length', description: 'number of characters per message to output', hasValue: true }
+  ],
   help: `
     Tails a topic in Kafka. Note: kafka:tail is not available in Heroku Private Spaces.
 
@@ -88,6 +91,7 @@ let cmd = {
 
     $ heroku kafka:topics:tail page-visits
     $ heroku kafka:topics:tail page-visits kafka-aerodynamic-32763
+    $ heroku kafka:topics:tail page-visits --max-length 200
 `,
   needsApp: true,
   needsAuth: true,
diff --git a/test/commands/topics_tail_test.js b/test/commands/topics_tail_test.js
index f7dfc67..0e7a195 100644
--- a/test/commands/topics_tail_test.js
+++ b/test/commands/topics_tail_test.js
@@ -129,13 +129,38 @@ describe('kafka:topics:tail', () => {
       tail.process.emit('SIGINT')
     }
 
-    return cmd.run({app: 'myapp', args: { TOPIC: 'topic-1' }})
+    return cmd.run({app: 'myapp', args: { TOPIC: 'topic-1' }, flags: {}})
       .then(() => {
         expect(cli.stdout).to.equal('topic-1 42 1 5 hello\ntopic-1 42 2 5 world\ntopic-1 42 3 0 NULL\n')
         expect(cli.stderr).to.be.empty
       })
   })
 
+  it('tails a topic and prints the results limited by max-length flag', () => {
+    api.get('/apps/myapp/config-vars').reply(200, config)
+    api.get('/apps/myapp/addon-attachments/kafka-1')
+      .reply(200, { name: 'KAFKA', config_vars: stockConfigVars, app: { name: 'sushi' } })
+
+    consumer.subscribe = (topic, callback) => {
+      callback([
+        { offset: 1, message: { value: Buffer.from('hello, this is a slightly longer message that shows an output just a litte bit longer than 80') } },
+        { offset: 2, message: { value: Buffer.from('Hodor. Hodor hodor... Hodor hodor hodor hodor. Hodor, hodor. Hodor. Hodor, hodor, hodor. Hodor hodor?! Hodor, hodor.') } },
+        { offset: 3, message: { value: Buffer.from('world') } },
+        { offset: 4, message: { value: null } }
+      ], undefined, 42)
+      tail.process.emit('SIGINT')
+    }
+
+    return cmd.run({app: 'myapp', args: { TOPIC: 'topic-1' }, flags: { 'max-length': '100' }})
+      .then(() => {
+        expect(cli.stdout).to.equal('topic-1 42 1 93 hello, this is a slightly longer message that shows an output just a litte bit longer than 80\n' +
+                                    'topic-1 42 2 116 Hodor. Hodor hodor... Hodor hodor hodor hodor. Hodor, hodor. Hodor. Hodor, hodor, hodor. Hodor hodor\n' +
+                                    'topic-1 42 3 5 world\n' +
+                                    'topic-1 42 4 0 NULL\n')
+        expect(cli.stderr).to.be.empty
+      })
+  })
+
   it('tails a topic with a prefix and prints the results', () => {
     let configWithPrefix = Object.assign({
       KAFKA_PREFIX: 'nile-1234.'
@@ -154,7 +179,7 @@ describe('kafka:topics:tail', () => {
       tail.process.emit('SIGINT')
     }
 
-    return cmd.run({app: 'myapp', args: { TOPIC: 'topic-1' }})
+    return cmd.run({app: 'myapp', args: { TOPIC: 'topic-1' }, flags: {}})
       .then(() => {
         expect(cli.stdout).to.equal('topic-1 42 1 5 hello\ntopic-1 42 2 5 world\ntopic-1 42 3 0 NULL\n')
         expect(cli.stderr).to.be.empty
@@ -179,7 +204,7 @@ describe('kafka:topics:tail', () => {
       tail.process.emit('SIGINT')
     }
 
-    return cmd.run({app: 'myapp', args: { TOPIC: 'nile-1234.topic-1' }})
+    return cmd.run({app: 'myapp', args: { TOPIC: 'nile-1234.topic-1' }, flags: {}})
       .then(() => {
         expect(cli.stdout).to.equal('nile-1234.topic-1 42 1 5 hello\nnile-1234.topic-1 42 2 5 world\nnile-1234.topic-1 42 3 0 NULL\n')
         expect(cli.stderr).to.be.empty