tests/exec: add test for exit code from exec

Execs should return the exit code of the exec'd process, if it started.

Signed-off-by: Laura Brehm <laurabrehm@hey.com>

tests/integration/models_containers_test.py

@@ -353,6 +353,15 @@ def test_exec_run_success(self):
         assert exec_output[0] == 0
         assert exec_output[1] == b"hello\n"
 
+    def test_exec_run_error_code_from_exec(self):
+        client = docker.from_env(version=TEST_API_VERSION)
+        container = client.containers.run(
+            "alpine", "sleep 20", detach=True
+        )
+        self.tmp_containers.append(container.id)
+        exec_output = container.exec_run("sh -c 'exit 42'")
+        assert exec_output[0] == 42
+
     def test_exec_run_failed(self):
         client = docker.from_env(version=TEST_API_VERSION)
         container = client.containers.run(
@@ -363,7 +372,7 @@ def test_exec_run_failed(self):
         # older versions of docker return `126` in the case that an exec cannot
         # be started due to a missing executable. We're fixing this for the
         # future, so accept both for now.
-        assert exec_output[0] == 127 or exec_output == 126
+        assert exec_output[0] == 127 or exec_output[0] == 126
 
     def test_kill(self):
         client = docker.from_env(version=TEST_API_VERSION)