Make an emulator channel include the more stable channels

emu/emu_downloads_menu.py

@@ -335,14 +335,22 @@ def find_image(regexpr):
 
 
 def find_emulator(channel):
-    """Displayes an interactive menu to select a released emulator binary.
+    """Finds the released emulator binaries for the given channel.
 
-    Returns a ImuInfo object with the choice or None if the user aborts."""
-    emu_infos = [
-        x
-        for x in get_emus_info()
-        if "linux" in x.urls and (channel == "all" or x.channel == channel)
-    ]
+    As with sdkmanager, a channel includes the more stable channels below it:
+    "canary" gives the newest emulator published on any channel, "stable" the
+    newest stable one. "all" gives every published emulator.
+
+    Returns a list of EmuInfo objects."""
+    emu_infos = [x for x in get_emus_info() if "linux" in x.urls]
+    if channel != "all":
+        channels = list(CHANNEL_MAPPING.values())
+        included = channels[: channels.index(channel) + 1] if channel in channels else []
+        emu_infos = [x for x in emu_infos if x.channel in included]
+        # Only the newest one, so a channel still stands for a single emulator.
+        emu_infos = sorted(
+            emu_infos, key=lambda x: [int(n) for n in x.version.split(".")], reverse=True
+        )[:1]
     logging.info("Found %s matching images: %s", channel, [str(x) for x in emu_infos])
     if not emu_infos:
         raise EmulatorNotFoundException(f"No emulator found in channel {channel}")

tests/test_find_emulator.py

@@ -0,0 +1,117 @@
+# Copyright 2026 The Android Open Source Project
+#
+# 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.
+"""Unit tests for find_emulator: a channel includes the more stable channels
+below it, as it does for sdkmanager."""
+import unittest.mock as mock
+
+import pytest
+import requests
+
+import emu.emu_downloads_menu as menu
+
+
+def _emu_pkg(channel, version, hostos="linux"):
+    """Build an emulator <remotePackage> snippet shaped like the real SDK XML."""
+    major, minor, micro = version.split(".")
+    return f"""
+<remotePackage path="emulator">
+  <revision><major>{major}</major><minor>{minor}</minor><micro>{micro}</micro></revision>
+  <uses-license ref="android-sdk-license"/>
+  <channelRef ref="{channel}"/>
+  <archives>
+    <archive><complete><url>emulator-{version}.zip</url></complete><host-os>{hostos}</host-os></archive>
+  </archives>
+</remotePackage>"""
+
+
+def _mock_repo(monkeypatch, packages):
+    xml = """<?xml version="1.0" ?>
+<sdk-repository>
+  <license id="android-sdk-license" type="text">Terms</license>
+  {}
+</sdk-repository>""".format("".join(packages))
+
+    def mock_get(url):
+        return mock.MagicMock(content=xml, status_code=200)
+
+    monkeypatch.setattr(requests, "get", mock_get)
+
+
+# The version numbers below are made up: only their order and the channel they
+# are published on matter.
+
+
+@pytest.fixture
+def stable_and_dev(monkeypatch):
+    """What the repository usually holds: the pre-release emulator is published
+    on channel-2, and nothing on channel-3."""
+    _mock_repo(
+        monkeypatch,
+        [_emu_pkg("channel-2", "2.0.0"), _emu_pkg("channel-0", "1.0.0")],
+    )
+
+
+@pytest.mark.parametrize(
+    "channel, expected",
+    [
+        ("stable", ["stable 1.0.0"]),
+        ("beta", ["stable 1.0.0"]),
+        ("dev", ["dev 2.0.0"]),
+        ("canary", ["dev 2.0.0"]),
+        ("all", ["dev 2.0.0", "stable 1.0.0"]),
+    ],
+)
+def test_channel_includes_more_stable_channels(stable_and_dev, channel, expected):
+    assert [str(x) for x in menu.find_emulator(channel)] == expected
+
+
+def test_canary_prefers_newest_release(monkeypatch):
+    _mock_repo(
+        monkeypatch,
+        [
+            _emu_pkg("channel-0", "1.0.0"),
+            _emu_pkg("channel-3", "1.10.0"),
+            _emu_pkg("channel-2", "1.9.0"),
+        ],
+    )
+    # Compared as numbers: 1.10.0 is newer than 1.9.0.
+    assert [str(x) for x in menu.find_emulator("canary")] == ["canary 1.10.0"]
+    assert [str(x) for x in menu.find_emulator("dev")] == ["dev 1.9.0"]
+
+
+def test_canary_gives_stable_when_it_is_the_newest(monkeypatch):
+    _mock_repo(
+        monkeypatch,
+        [_emu_pkg("channel-3", "1.0.0"), _emu_pkg("channel-0", "2.0.0")],
+    )
+    assert [str(x) for x in menu.find_emulator("canary")] == ["stable 2.0.0"]
+
+
+def test_stable_does_not_include_less_stable_channels(monkeypatch):
+    _mock_repo(monkeypatch, [_emu_pkg("channel-2", "2.0.0")])
+    with pytest.raises(menu.EmulatorNotFoundException):
+        menu.find_emulator("stable")
+
+
+def test_emulator_without_linux_build_is_skipped(monkeypatch):
+    _mock_repo(
+        monkeypatch,
+        [_emu_pkg("channel-2", "2.0.0", hostos="macosx"), _emu_pkg("channel-0", "1.0.0")],
+    )
+    assert [str(x) for x in menu.find_emulator("canary")] == ["stable 1.0.0"]
+
+
+def test_unknown_channel_finds_nothing(stable_and_dev):
+    with pytest.raises(menu.EmulatorNotFoundException):
+        menu.find_emulator("nightly")