diff --git a/pyinfra/server/bufferizer/lazy_bufferizer.py b/pyinfra/server/bufferizer/lazy_bufferizer.py
index ad40312..d394cca 100644
--- a/pyinfra/server/bufferizer/lazy_bufferizer.py
+++ b/pyinfra/server/bufferizer/lazy_bufferizer.py
@@ -54,13 +54,13 @@ class StreamBuffer:
         yield from takewhile(is_not_nothing, repeatedly(self.pop))
 
     def push(self, item):
+        self.result_stream = chain(self.result_stream, self.compute(item))
+
+    def compute(self, item):
         try:
-            self.result_stream = chain(self.result_stream, self.compute(item))
+            yield from self.fn(item)
         except TypeError as err:
             raise TypeError("Function failed with type error. Is it mappable?") from err
 
-    def compute(self, item):
-        yield from self.fn(item)
-
     def pop(self):
         return first(chain(self.result_stream, [Nothing]))
diff --git a/pyinfra/utils/func.py b/pyinfra/utils/func.py
index fed8161..cf5e308 100644
--- a/pyinfra/utils/func.py
+++ b/pyinfra/utils/func.py
@@ -31,6 +31,11 @@ def duplicate_stream_and_apply(f1, f2):
     return compose(star(parallel(f1, f2)), tee)
 
 
+def foreach(fn, iterable):
+    for itm in iterable:
+        fn(itm)
+
+
 def parallel_map(f1, f2):
     """Applies functions to a stream in parallel and yields a stream of tuples:
     parallel_map :: a -> b, a -> c -> [a] -> [(b, c)]
diff --git a/test/unit_tests/server/stream_buffer_test.py b/test/unit_tests/server/stream_buffer_test.py
index 966e3c9..fb43386 100644
--- a/test/unit_tests/server/stream_buffer_test.py
+++ b/test/unit_tests/server/stream_buffer_test.py
@@ -1,17 +1,62 @@
-from itertools import chain
-
 import pytest
+from funcy import repeatedly, takewhile, notnone, lmap, lmapcat
 
-from pyinfra.server.bufferizer.lazy_bufferizer import StreamBuffer
+from pyinfra.server.bufferizer.lazy_bufferizer import FlatStreamBuffer, StreamBuffer
 from pyinfra.server.dispatcher.dispatcher import Nothing
-from pyinfra.utils.func import lift
+from pyinfra.server.server import LazyProcessor
+from pyinfra.utils.func import lift, foreach
 
 
-@pytest.mark.parametrize("buffer_size", [0, 1, 3, 10, 12])
-def test_stream_buffer(buffer_size):
-    def func(x):
+@pytest.fixture
+def func():
+    def fn(x):
         return x ** 2
 
-    func = StreamBuffer(lift(func))
+    return fn
 
-    assert list(chain(*map(func, [*range(10), Nothing]))) == [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
+
+def test_stream_buffer(func, inputs, outputs, buffer_size):
+    stream_buffer = StreamBuffer(lift(func), buffer_size=buffer_size)
+
+    assert lmapcat(stream_buffer, (*inputs, Nothing)) == outputs
+    assert lmapcat(stream_buffer, [Nothing]) == []
+
+
+@pytest.mark.parametrize("n_items", [1])
+def test_stream_buffer_catches_type_error(func, inputs, outputs):
+
+    stream_buffer = StreamBuffer(func)
+
+    with pytest.raises(TypeError):
+        lmapcat(stream_buffer, inputs)
+
+
+def test_flat_stream_buffer(func, inputs, outputs, buffer_size):
+    flat_stream_buffer = FlatStreamBuffer(lift(func), buffer_size=buffer_size)
+
+    assert list(flat_stream_buffer(inputs)) == outputs
+    assert list(flat_stream_buffer([])) == []
+
+
+def test_lazy_processor(func, inputs, outputs):
+    stream_buffer = FlatStreamBuffer(lift(func))
+    lazy_processor = LazyProcessor(stream_buffer)
+
+    foreach(lazy_processor.push, inputs)
+
+    assert list(takewhile(notnone, repeatedly(lazy_processor.pop))) == outputs
+
+
+@pytest.fixture
+def inputs(n_items):
+    return range(n_items)
+
+
+@pytest.fixture
+def outputs(inputs, func):
+    return lmap(func, inputs)
+
+
+@pytest.fixture(params=[0, 1, 3, 10, 12])
+def buffer_size(request):
+    return request.param