tests/lib: Add a new unittest type to simplify launching test programs

We were reusing the same logic everywhere, while we can just reuse an
unique class to base our tests on that avoids having to copy-and-paste
code for no good reason

tests/lib/testprogramrunner.py

@@ -0,0 +1,153 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+#
+# Copyright © 2018 Endless Mobile, Inc.
+# Copyright © 2025 Canonical Ltd.
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+# MA  02110-1301  USA
+
+"""Integration tests for GLib utilities."""
+
+import os
+import shutil
+import subprocess
+import tempfile
+import unittest
+import sys
+
+from dataclasses import dataclass
+from enum import Enum
+
+
+class ProgramType(Enum):
+    """Enum to define the kind of tool to use"""
+
+    NATIVE = 1
+    INTERPRETED = 2
+
+
+@dataclass
+class Result:
+    """Class for keeping track of the executable result."""
+
+    info: subprocess.CompletedProcess
+    out: str
+    err: str
+    subs: dict
+
+
+class TestProgramRunner(unittest.TestCase):
+    """Integration test for running glib-based tools.
+
+    This can be run when installed or uninstalled. When uninstalled, it
+    requires G_TEST_BUILDDIR or _G_TEST_PROGRAM_RUNNER_PATH to be set.
+    """
+
+    PROGRAM_NAME: str = None
+    PROGRAM_TYPE: ProgramType = ProgramType.NATIVE
+    INTERPRETER: str = None
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.assertTrue(cls.PROGRAM_NAME, "class PROGRAM_NAME must be set")
+
+        ext = ""
+        if cls.PROGRAM_TYPE == ProgramType.NATIVE and os.name == "nt":
+            ext = ".exe"
+
+        cls._program_name = f"{cls.PROGRAM_NAME}{ext}"
+
+        if "_G_TEST_PROGRAM_RUNNER_PATH" in os.environ:
+            cls.__program = os.path.join(
+                os.environ["_G_TEST_PROGRAM_RUNNER_PATH"], cls._program_name
+            )
+        elif "G_TEST_BUILDDIR" in os.environ:
+            cls.__program = os.path.join(
+                os.environ["G_TEST_BUILDDIR"], cls._program_name
+            )
+        else:
+            cls.__program = os.path.join(os.path.dirname(__file__), cls._program_name)
+            if not os.path.exists(cls.__program):
+                cls.__program = shutil.which(cls._program_name)
+
+    def setUp(self):
+        print(f"{self.PROGRAM_NAME}: {self.__program}")
+        self.assertTrue(os.path.exists(self.__program))
+
+        self.tmpdir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmpdir.cleanup)
+        old_cwd = os.getcwd()
+        self.addCleanup(os.chdir, old_cwd)
+        os.chdir(self.tmpdir.name)
+        print("tmpdir:", self.tmpdir.name)
+
+    def runTestProgram(
+        self, *args, should_fail=False, timeout_seconds=10, wrapper_args=[]
+    ) -> Result:
+        argv = [self.__program]
+
+        argv.extend(*args)
+
+        # shebang lines are not supported on native
+        # Windows consoles
+        if self.PROGRAM_TYPE == ProgramType.INTERPRETED and os.name == "nt":
+            argv.insert(0, self.INTERPRETER if self.INTERPRETER else sys.executable)
+
+        argv = wrapper_args + argv
+
+        env = os.environ.copy()
+        env["LC_ALL"] = "C.UTF-8"
+        env["G_DEBUG"] = "fatal-warnings"
+
+        print("Running:", argv)
+
+        # We want to ensure consistent line endings...
+        info = subprocess.run(
+            argv,
+            timeout=timeout_seconds,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            env=env,
+            universal_newlines=True,
+            text=True,
+            encoding="utf-8",
+            check=False,
+        )
+
+        result = Result(
+            info=info,
+            out=info.stdout.strip(),
+            err=info.stderr.strip(),
+            subs=self._getSubs(),
+        )
+
+        print("Return code:", result.info.returncode)
+        print("Output:\n", result.out)
+        print("Error:\n", result.err)
+
+        if should_fail:
+            with self.assertRaises(subprocess.CalledProcessError):
+                info.check_returncode()
+        else:
+            info.check_returncode()
+
+        return result
+
+    def _getSubs(self) -> dict:
+        return {}