Try to support prompt_toolkit >3.0.37

Currently one test will fail with latest prompt_toolkit(3.0.43).
test_blank_line_fix will throw RuntimeError: no running event loop.
By bisecting commit, the culprit is
prompt-toolkit/python-prompt-toolkit@a775996.
This commit replaces custom `get_event_loop` with `asyncio.get_event_loop`. The former will creator a new loop if `asyncio.get_running_loop` fails while the latter won't.
I mimic the changes in the examples to use `asyncio.run` and the test
passes. I'm not sure whether more changes are needed.

Fixes: #344

pyproject.toml

@@ -33,7 +33,7 @@ license = "MIT"
 
 [tool.poetry.dependencies]
 python = ">=3.8"
-prompt_toolkit = ">=2.0,<=3.0.36"  # once https://github.com/prompt-toolkit/python-prompt-toolkit/issues/1726 is fixed, this can be changed to ">=2.0,<4.0"
+prompt_toolkit = ">=2.0,<4.0"  # once https://github.com/prompt-toolkit/python-prompt-toolkit/issues/1726 is fixed, this can be changed to ">=2.0,<4.0"
 
 [tool.poetry.group.docs]
 optional = true

tests/prompts/test_common.py

@@ -1,11 +1,14 @@
+import asyncio
 from unittest.mock import Mock
 from unittest.mock import call
 
 import pytest
+import prompt_toolkit
 from prompt_toolkit.document import Document
 from prompt_toolkit.output import DummyOutput
 from prompt_toolkit.styles import Attrs
 from prompt_toolkit.validation import ValidationError
+from prompt_toolkit.input.defaults import create_pipe_input
 from prompt_toolkit.validation import Validator
 
 from questionary import Choice
@@ -72,21 +75,41 @@ def get_prompt_tokens():
 
     ic = InquirerControl(["a", "b", "c"])
 
-    def run(inp):
-        inp.send_text("")
-        layout = common.create_inquirer_layout(
-            ic, get_prompt_tokens, input=inp, output=DummyOutput()
-        )
-
-        # usually this would be 2000000000000000000000000000000
-        # but `common._fix_unecessary_blank_lines` makes sure
-        # the main window is not as greedy (avoiding blank lines)
-        assert (
-            layout.container.preferred_height(100, 200).max
-            == 1000000000000000000000000000001
-        )
-
-    execute_with_input_pipe(run)
+    prompt_toolkit_version = tuple([int(v) for v in prompt_toolkit.VERSION])
+
+    if prompt_toolkit_version >= (3, 0, 37):
+        async def run(inp):
+            inp.send_text("")
+            layout = common.create_inquirer_layout(
+                ic, get_prompt_tokens, input=inp, output=DummyOutput()
+            )
+
+            # usually this would be 2000000000000000000000000000000
+            # but `common._fix_unecessary_blank_lines` makes sure
+            # the main window is not as greedy (avoiding blank lines)
+            assert (
+                layout.container.preferred_height(100, 200).max
+                == 1000000000000000000000000000001
+            )
+        with create_pipe_input() as inp:
+            asyncio.run(run(inp))
+
+    else:
+        def run(inp):
+            inp.send_text("")
+            layout = common.create_inquirer_layout(
+                ic, get_prompt_tokens, input=inp, output=DummyOutput()
+            )
+
+            # usually this would be 2000000000000000000000000000000
+            # but `common._fix_unecessary_blank_lines` makes sure
+            # the main window is not as greedy (avoiding blank lines)
+            assert (
+                layout.container.preferred_height(100, 200).max
+                == 1000000000000000000000000000001
+            )
+
+        execute_with_input_pipe(run)
 
 
 def test_prompt_highlight_coexist():