feat(utils): add get_random_choice

mergify_engine/tests/unit/flycheck_test_utils.py

@@ -0,0 +1,79 @@
+#
+# Copyright © 2019–2020 Mergify SAS
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+import pytest
+
+from mergify_engine import utils
+
+
+def test_unicode_truncate():
+    s = "hé ho! how are you√2?"
+    assert utils.unicode_truncate(s, 0) == ""
+    assert utils.unicode_truncate(s, 1) == "h"
+    assert utils.unicode_truncate(s, 2) == "h"
+    assert utils.unicode_truncate(s, 3) == "hé"
+    assert utils.unicode_truncate(s, 4) == "hé "
+    assert utils.unicode_truncate(s, 10) == "hé ho! ho"
+    assert utils.unicode_truncate(s, 18) == "hé ho! how are yo"
+    assert utils.unicode_truncate(s, 19) == "hé ho! how are you"
+    assert utils.unicode_truncate(s, 20) == "hé ho! how are you"
+    assert utils.unicode_truncate(s, 21) == "hé ho! how are you"
+    assert utils.unicode_truncate(s, 22) == "hé ho! how are you√"
+    assert utils.unicode_truncate(s, 23) == "hé ho! how are you√2"
+    assert utils.unicode_truncate(s, 50) == s
+
+
+def test_process_identifier():
+    assert isinstance(utils._PROCESS_IDENTIFIER, str)
+
+
+def test_get_random_choices():
+    choices = {
+        "jd": 10,
+        "sileht": 1,
+        "foobar": 3,
+    }
+    assert utils.get_random_choices(0, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(1, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(2, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(3, choices, 1) == {"jd"}
+    assert utils.get_random_choices(4, choices, 1) == {"jd"}
+    assert utils.get_random_choices(11, choices, 1) == {"jd"}
+    assert utils.get_random_choices(12, choices, 1) == {"jd"}
+    assert utils.get_random_choices(13, choices, 1) == {"sileht"}
+    assert utils.get_random_choices(14, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(15, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(16, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(17, choices, 1) == {"jd"}
+    assert utils.get_random_choices(18, choices, 1) == {"jd"}
+    assert utils.get_random_choices(19, choices, 1) == {"jd"}
+    assert utils.get_random_choices(20, choices, 1) == {"jd"}
+    assert utils.get_random_choices(21, choices, 1) == {"jd"}
+    assert utils.get_random_choices(22, choices, 1) == {"jd"}
+    assert utils.get_random_choices(23, choices, 1) == {"jd"}
+    assert utils.get_random_choices(24, choices, 1) == {"jd"}
+    assert utils.get_random_choices(25, choices, 1) == {"jd"}
+    assert utils.get_random_choices(26, choices, 1) == {"jd"}
+    assert utils.get_random_choices(27, choices, 1) == {"sileht"}
+    assert utils.get_random_choices(28, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(29, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(30, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(31, choices, 1) == {"jd"}
+    assert utils.get_random_choices(32, choices, 1) == {"jd"}
+    assert utils.get_random_choices(23, choices, 2) == {"sileht", "jd"}
+    assert utils.get_random_choices(2, choices, 2) == {"jd", "foobar"}
+    assert utils.get_random_choices(4, choices, 2) == {"jd", "foobar"}
+    assert utils.get_random_choices(0, choices, 3) == {"jd", "sileht", "foobar"}
+    with pytest.raises(ValueError):
+        assert utils.get_random_choices(4, choices, 4) == {"jd", "sileht"}

mergify_engine/tests/unit/test_utils.py

@@ -1,3 +1,19 @@
+#
+# Copyright © 2019–2020 Mergify SAS
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+import pytest
+
 from mergify_engine import utils
 
 
@@ -20,3 +36,44 @@ def test_unicode_truncate():
 
 def test_process_identifier():
     assert isinstance(utils._PROCESS_IDENTIFIER, str)
+
+
+def test_get_random_choices():
+    choices = {
+        "jd": 10,
+        "sileht": 1,
+        "foobar": 3,
+    }
+    assert utils.get_random_choices(0, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(1, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(2, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(3, choices, 1) == {"jd"}
+    assert utils.get_random_choices(4, choices, 1) == {"jd"}
+    assert utils.get_random_choices(11, choices, 1) == {"jd"}
+    assert utils.get_random_choices(12, choices, 1) == {"jd"}
+    assert utils.get_random_choices(13, choices, 1) == {"sileht"}
+    assert utils.get_random_choices(14, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(15, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(16, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(17, choices, 1) == {"jd"}
+    assert utils.get_random_choices(18, choices, 1) == {"jd"}
+    assert utils.get_random_choices(19, choices, 1) == {"jd"}
+    assert utils.get_random_choices(20, choices, 1) == {"jd"}
+    assert utils.get_random_choices(21, choices, 1) == {"jd"}
+    assert utils.get_random_choices(22, choices, 1) == {"jd"}
+    assert utils.get_random_choices(23, choices, 1) == {"jd"}
+    assert utils.get_random_choices(24, choices, 1) == {"jd"}
+    assert utils.get_random_choices(25, choices, 1) == {"jd"}
+    assert utils.get_random_choices(26, choices, 1) == {"jd"}
+    assert utils.get_random_choices(27, choices, 1) == {"sileht"}
+    assert utils.get_random_choices(28, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(29, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(30, choices, 1) == {"foobar"}
+    assert utils.get_random_choices(31, choices, 1) == {"jd"}
+    assert utils.get_random_choices(32, choices, 1) == {"jd"}
+    assert utils.get_random_choices(23, choices, 2) == {"sileht", "jd"}
+    assert utils.get_random_choices(2, choices, 2) == {"jd", "foobar"}
+    assert utils.get_random_choices(4, choices, 2) == {"jd", "foobar"}
+    assert utils.get_random_choices(0, choices, 3) == {"jd", "sileht", "foobar"}
+    with pytest.raises(ValueError):
+        assert utils.get_random_choices(4, choices, 4) == {"jd", "sileht"}

mergify_engine/utils.py

@@ -1,4 +1,5 @@
-# -*- encoding: utf-8 -*-
+#
+# Copyright © 2019–2020 Mergify SAS
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
 # not use this file except in compliance with the License. You may obtain
@@ -11,7 +12,6 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.
-
 import asyncio
 import datetime
 import hashlib
@@ -21,6 +21,7 @@
 import socket
 import subprocess
 import tempfile
+import typing
 import urllib.parse
 
 import aredis
@@ -143,3 +144,40 @@ def add_cred(self, username, password, path):
         parsed[2] = path
         url = urllib.parse.urlunparse(parsed)
         self("credential", "approve", input=f"url={url}\n\n".encode("utf8"))
+
+
+def get_random_choices(
+    random_number: int, population: typing.Dict[typing.Any, int], k: int = 1
+) -> set:
+    """Return a random number of item from a population without replacement.
+
+    You need to provide the random number yourself.
+
+    The output is always the same based on that number.
+
+    The population is a dict where the key is the choice and the value is the weight.
+
+    The argument k is the number of item that should be picked.
+
+    :param random_number: The random_number that should be picked.
+    :param population: The dict of {item: weight}.
+    :param k: The number of choices to make.
+    :return: A set with the choices.
+    """
+    picked = set()
+    population = population.copy()
+
+    if k > len(population):
+        raise ValueError("k cannot be greater than the population size")
+
+    while len(picked) < k:
+        total_weight = sum(population.values())
+        choice_index = (random_number % total_weight) + 1
+        for item in sorted(population):
+            choice_index -= population[item]
+            if choice_index <= 0:
+                picked.add(item)
+                del population[item]
+                break
+
+    return picked