stream: allow returning null from pipeline tail

PR-URL: nodejs#42078 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
sxa · Mar 7, 2022 · 53338fe · 53338fe
1 parent a32ec98
commit 53338fe
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diff --git a/lib/internal/streams/pipeline.js b/lib/internal/streams/pipeline.js
@@ -265,7 +265,9 @@ function pipelineImpl(streams, callback, opts) {
           then.call(ret,
                     (val) => {
                       value = val;
-                      pt.write(val);
+                      if (val != null) {
+                        pt.write(val);
+                      }
                       if (end) {
                         pt.end();
                       }

diff --git a/test/parallel/test-stream-pipeline.js b/test/parallel/test-stream-pipeline.js
@@ -1511,3 +1511,18 @@ const tsp = require('timers/promises');
     assert.strictEqual(s.destroyed, true);
   }));
 }
+
+{
+  const s = new PassThrough({ objectMode: true });
+  pipeline(async function*() {
+    await Promise.resolve();
+    yield 'hello';
+    yield 'world';
+    yield 'world';
+  }, s, async function(source) {
+    return null;
+  }, common.mustCall((err, val) => {
+    assert.strictEqual(err, undefined);
+    assert.strictEqual(val, null);
+  }));
+}