feat: allow to override slack channel when using webhook (#81)

Currently, there is a logic to throw an error when only `SLACK_CHANNEL` is specified but not `SLACK_TOKEN`. When using incoming webhook, a developer can override the slack channel to send a notification to by specifying the `channel` param for the post request. This commit changes the logic so that a developer can use specify `SLACK_WEBHOOK` and `SLACK_CHANNEL` to override the default channel associated to the webhook. Co-authored-by: Yoshi <[email protected]>
juliuscc · Dec 27, 2021 · 83b4699 · 83b4699
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diff --git a/README.md b/README.md
@@ -62,6 +62,17 @@ With this example:
 - Slack notifications are sent on a failure or successful release from branch "master"
 - Slack notifications are skipped on all other branches
 
+#### Note
+
+[The official documentation](https://api.slack.com/messaging/webhooks) says that a developer cannot
+override the default channel or icon that are associated with the webhook, but some users of this
+library reported that they were able to.
+
+- use `slackIcon` (or `SLACK_ICON` env var) for overriding slack icon
+- use `slackChannel` (or `SLACK_CHANNEL` env var) for overriding slack channel
+
+**WARNING: This is not mentioned in the official documentation, so use at your own risk.**
+
 ## Slack Access Token/Channel Usage
 
 This configuration can be used with a [**bot**](https://api.slack.com/authentication/token-types#bot) Slack Access token with minimum permissions of `chat:write`.
@@ -136,12 +147,13 @@ Options can be defined in the environment where you will run semantic release. T
 
 Alternatively, you can pass the webhook as a configuration option or use an Access Token.
 
-| Variable                   | Description                                                                          |
-| -------------------------- | ------------------------------------------------------------------------------------ |
-| `SLACK_WEBHOOK`            | Slack webhook created when adding app to workspace.                                  |
-| `SLACK_TOKEN`              | Slack bot Access token.                                                              |
-| `SLACK_CHANNEL`            | Slack channel name or id to send notifications to (must be used with `SLACK_TOKEN`). |
-| `SEMANTIC_RELEASE_PACKAGE` | Override or add package name instead of npm package name                             |
+| Variable                   | Description                                              |
+| -------------------------- | -------------------------------------------------------- |
+| `SLACK_WEBHOOK`            | Slack webhook created when adding app to workspace.      |
+| `SLACK_TOKEN`              | Slack bot Access token.                                  |
+| `SLACK_CHANNEL`            | Slack channel name or id to send notifications to.       |
+| `SLACK_ICON`               | Slack bot app icon.                                      |
+| `SEMANTIC_RELEASE_PACKAGE` | Override or add package name instead of npm package name |
 
 ### Options
 

diff --git a/lib/postMessage.js b/lib/postMessage.js
@@ -25,6 +25,9 @@ module.exports = async (
         body: JSON.stringify(message)
       })
     } else {
+      if (slackChannel) {
+        message.channel = slackChannel
+      }
       response = await fetch(slackWebhook, {
         method: 'post',
         headers: {

diff --git a/lib/verifyConditions.js b/lib/verifyConditions.js
@@ -7,22 +7,12 @@ module.exports = (pluginConfig, context) => {
     slackWebhook,
     slackWebhookEnVar,
     slackToken,
-    slackTokenEnVar,
     slackChannel,
     slackChannelEnVar
   } = getSlackVars(pluginConfig)
 
-  if (slackChannel || slackToken) {
-    if (!slackToken) {
-      logger.log(
-        'SLACK_CHANNEL must be used with SLACK_TOKEN which has not been defined.'
-      )
-      throw new SemanticReleaseError(
-        'No Slack token defined.',
-        'ENOSLACKTOKEN',
-        `A Slack Token must be created and set in the \`${slackTokenEnVar}\` environment variable on your CI environment.\n\n\nPlease make sure to create a Slack Token and to set it in the \`${slackTokenEnVar}\` environment variable on your CI environment. Alternatively, provide \`slackToken\` as a configuration option.`
-      )
-    } else if (!slackChannel) {
+  if (slackToken) {
+    if (!slackChannel) {
       logger.log(
         'SLACK_TOKEN must be used with SLACK_CHANNEL which has not been defined.'
       )

diff --git a/test/verifyConditions.test.js b/test/verifyConditions.test.js
@@ -85,40 +85,6 @@ describe('test verifyConditions', () => {
       return `A Slack Channel must be created and set in the \`${slackChannelEnVar}\` environment variable on your CI environment.\n\n\nPlease make sure to set a Slack Channel in the \`${slackChannelEnVar}\` environment variable on your CI environment. Alternatively, provide \`slackChannel\` as a configuration option.`
     }
 
-    it('should throw if neither slackToken and environment variable SLACK_TOKEN are set but slackChannel is', () => {
-      assert.throws(
-        () =>
-          verifyConditions(
-            { ...defaultPluginConfig, slackChannel: 'some channel' },
-            fakeContext
-          ),
-        new SemanticReleaseError(
-          'No Slack token defined.',
-          'ENOSLACKTOKEN',
-          getMissingTokenError('SLACK_TOKEN')
-        )
-      )
-    })
-
-    it('should throw if slackChannel is set, slackToken is not set and slackTokenEnVar give an empty environment variable', () => {
-      assert.throws(
-        () =>
-          verifyConditions(
-            {
-              ...defaultPluginConfig,
-              slackChannel: 'some channel',
-              slackTokenEnVar: 'CUSTOM_TOKEN'
-            },
-            fakeContext
-          ),
-        new SemanticReleaseError(
-          'No Slack token defined.',
-          'ENOSLACKTOKEN',
-          getMissingTokenError('CUSTOM_TOKEN')
-        )
-      )
-    })
-
     it('should throw if neither slackChannel and environment variable SLACK_CHANNEL are set but slackToken is', () => {
       assert.throws(
         () =>