feat: add cap method and relative test case

src/index.ts

@@ -110,7 +110,7 @@ export default function(ary?: Source<any>[]) {
     next()
   }
 
-  read.add = function(stream: Source<any>) {
+  read.add = function(stream?: Source<any>) {
     if (!stream) {
       // the stream will now end when all the streams end.
       capped = true
@@ -121,5 +121,9 @@ export default function(ary?: Source<any>[]) {
     next()
   }
 
+  read.cap = function() {
+    read.add()
+  }
+
   return read
 }

test/add.test.ts

@@ -0,0 +1,58 @@
+import * as pull from 'pull-stream'
+import many from '../src/'
+
+describe('add', () => {
+  it('add after stream creation', done => {
+    const m = many()
+
+    pull(
+      m,
+      pull.collect(function(err, ary) {
+        expect(err).toBeFalsy()
+        expect(ary.sort()).toEqual([1, 2, 3, 4, 5, 6])
+        done()
+      })
+    )
+    m.add(pull.values([1, 2, 3]))
+    m.add(pull.values([4, 5, 6]))
+    m.add()
+  })
+
+  it('add after stream creation - more', done => {
+    const m = many()
+
+    pull(
+      m,
+      pull.collect(function(err, ary) {
+        expect(err).toBeFalsy()
+        expect(ary.sort()).toEqual([])
+        done()
+      })
+    )
+    m.add()
+  })
+
+  it('do not close inputs until the last minute', done => {
+    const m = many()
+    const seen: number[] = []
+
+    pull(
+      m,
+      pull.through(function(data) {
+        // wait until the last message to end inputs.
+        seen.push(data)
+        if (data >= 6) {
+          m.cap()
+        }
+      }),
+      pull.collect(function(err, ary) {
+        expect(err).toBeFalsy()
+        expect(ary.sort()).toEqual([1, 2, 3, 4, 5, 6])
+        expect(seen.sort()).toEqual([1, 2, 3, 4, 5, 6])
+        done()
+      })
+    )
+    m.add(pull.values([1, 2, 3]))
+    m.add(pull.values([4, 5, 6]))
+  })
+})