feat(command): add command finish hook

docs/advanced.md

@@ -447,6 +447,20 @@ yargs.parserConfiguration({
 See the [yargs-parser](https://github.com/yargs/yargs-parser#configuration) module
 for detailed documentation of this feature.
 
+## Command finish hook
+### Example
+```
+yargs
+    .comand('cmd', ..., async () => {
+        await this.model.find()
+        return Promise.resolve('result value')
+    })
+    .onFinishCommand(async (resultValue) => {
+        await this.db.disconnect()
+        process.exit()
+    }).argv;
+```
+
 ## Middleware
 
 Sometimes you might want to transform arguments before they reach the command handler.

lib/command.js

@@ -242,13 +242,23 @@ module.exports = function command (yargs, usage, validation, globalMiddleware) {
 
       if (isPromise(handlerResult)) {
         yargs.getUsageInstance().cacheHelpMessage()
-        handlerResult.catch(error => {
-          try {
-            yargs.getUsageInstance().fail(null, error)
-          } catch (err) {
+        handlerResult
+          .then(value => {
+            if (yargs._onFinishCommand) {
+              return yargs._onFinishCommand(value)
+            }
+          })
+          .catch(error => {
+            try {
+              yargs.getUsageInstance().fail(null, error)
+            } catch (err) {
             // fail's throwing would cause an unhandled rejection.
-          }
-        })
+            }
+          })
+      } else {
+        if (yargs._onFinishCommand) {
+          yargs._onFinishCommand(handlerResult)
+        }
       }
     }
 

test/yargs.js

@@ -2339,4 +2339,36 @@ describe('yargs dsl tests', () => {
         })
     })
   })
+
+  describe('onFinishCommand', () => {
+    it('use with promise', (done) => {
+      const result = 'noop-result'
+      yargs(['noop']).command('noop', 'a noop command', noop, () => {
+        return Promise.resolve(result)
+      }).onFinishCommand(async (commandResult) => {
+        commandResult.should.eql(result)
+      })
+        .parse('noop', (err, argv) => {
+          if (err) {
+            return done(err)
+          }
+          return done()
+        })
+    })
+
+    it('use without promise', (done) => {
+      const result = 'noop-result'
+      yargs(['noop']).command('noop', 'a noop command', noop, () => {
+        return result
+      }).onFinishCommand(async (commandResult) => {
+        commandResult.should.eql(result)
+      })
+        .parse('noop', (err, argv) => {
+          if (err) {
+            return done(err)
+          }
+          return done()
+        })
+    })
+  })
 })

yargs.js

@@ -483,6 +483,12 @@ function Yargs (processArgs, cwd, parentRequire) {
     return self
   }
 
+  self.onFinishCommand = function (f) {
+    argsert('<function>', [f], arguments.length)
+    self._onFinishCommand = f
+    return self
+  }
+
   self.check = function (f, _global) {
     argsert('<function> [boolean]', [f, _global], arguments.length)
     validation.check(f, _global !== false)