Wait for all containers to exit when running 'up' interactively

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

tests/unit/multiplexer_test.py

@@ -0,0 +1,28 @@
+import unittest
+
+from compose.cli.multiplexer import Multiplexer
+
+
+class MultiplexerTest(unittest.TestCase):
+    def test_no_iterators(self):
+        mux = Multiplexer([])
+        self.assertEqual([], list(mux.loop()))
+
+    def test_empty_iterators(self):
+        mux = Multiplexer([
+            (x for x in []),
+            (x for x in []),
+        ])
+
+        self.assertEqual([], list(mux.loop()))
+
+    def test_aggregates_output(self):
+        mux = Multiplexer([
+            (x for x in [0, 2, 4]),
+            (x for x in [1, 3, 5]),
+        ])
+
+        self.assertEqual(
+            [0, 1, 2, 3, 4, 5],
+            sorted(list(mux.loop())),
+        )