readable event emitted right away when listened for

Fix: #36

Author: isaacs

index.js

@@ -372,6 +372,8 @@ module.exports = class Minipass extends Stream {
     const ret = super.on(ev, fn)
     if (ev === 'data' && !this.pipes.length && !this.flowing)
       this[RESUME]()
+    else if (ev === 'readable' && this[BUFFERLENGTH] !== 0)
+      super.emit('readable')
     else if (isEndish(ev) && this[EMITTED_END]) {
       super.emit(ev)
       this.removeAllListeners(ev)

test/readable-emits-immediately.js

@@ -0,0 +1,14 @@
+// https://github.com/isaacs/minipass/issues/36
+const Minipass = require('../')
+const t = require('tap')
+
+const m = new Minipass({ encoding: 'utf8' })
+m.write('hello')
+t.equal(m.flowing, false)
+let readableEmitted = false
+m.on('readable', () => {
+  readableEmitted = true
+  m.on('data', c => t.equal(c, 'hello'))
+})
+t.equal(m.flowing, true)
+t.equal(readableEmitted, true)

test/write-returns-true-when-readable-triggers-flow.js

@@ -11,7 +11,14 @@ t.test('empty write', async t => {
   const p = dest.concat().then(d => t.equal(d, 'a', 'got data'))
   t.equal(s.write('a'), false, 'first write returns false')
   t.equal(s.write(''), false, 'empty write returns false')
-  s.on('readable', () => s.pipe(dest))
+  // since readable emits immediately, the NEXT one needs to trigger
+  let firstReadable = false
+  s.on('readable', () => {
+    if (!firstReadable)
+      firstReadable = true
+    else
+      s.pipe(dest)
+  })
   t.equal(s.flowing, false, 'src is not flowing yet')
   t.equal(s.write(''), true, 'return true, now flowing')
   s.end()
@@ -24,7 +31,14 @@ t.test('non-empty write', async t => {
   const p = dest.concat().then(d => t.equal(d, 'ab', 'got data'))
   t.equal(s.write('a'), false, 'first write returns false')
   t.equal(s.write(''), false, 'empty write returns false')
-  s.on('readable', () => s.pipe(dest))
+  // since readable emits immediately, the NEXT one needs to trigger
+  let firstReadable = false
+  s.on('readable', () => {
+    if (!firstReadable)
+      firstReadable = true
+    else
+      s.pipe(dest)
+  })
   t.equal(s.flowing, false, 'src is not flowing yet')
   t.equal(s.write('b'), true, 'return true, now flowing')
   s.end()