r.soillossbare: restore the user's region with a temporary region

src/raster/r.soillossbare/r.soillossbare.py

@@ -518,6 +518,9 @@ def main():
     if gs.verbosity() > 2:
         quiet = False
 
+    # Use a temporary region so the user's computational region is restored
+    # on exit instead of being left at the module's working resolution
+    gs.use_temp_region()
     gs.run_command("g.region", flags="a", res=resolution)
 
     if flowacc:

src/raster/r.soillossbare/testsuite/test_r_soillossbare.py

@@ -0,0 +1,65 @@
+import grass.script as gs
+
+from grass.gunittest.case import TestCase
+from grass.gunittest.main import test
+
+
+class TestRSoillossbare(TestCase):
+    elevation = "test_elevation"
+    kfactor = "test_kfactor"
+    rfactor = "test_rfactor"
+    output = "test_soillossbare"
+
+    @classmethod
+    def setUpClass(cls):
+        cls.use_temp_region()
+        cls.runModule("g.region", n=10, s=0, e=10, w=0, res=1)
+        cls.runModule(
+            "r.mapcalc", expression=f"{cls.elevation} = row() + col()", overwrite=True
+        )
+        cls.runModule("r.mapcalc", expression=f"{cls.kfactor} = 0.3", overwrite=True)
+        cls.runModule("r.mapcalc", expression=f"{cls.rfactor} = 100", overwrite=True)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.runModule(
+            "g.remove",
+            flags="f",
+            type="raster",
+            name=[cls.elevation, cls.kfactor, cls.rfactor],
+        )
+        cls.del_temp_region()
+
+    def tearDown(self):
+        self.runModule("g.remove", flags="f", type="raster", name=self.output)
+
+    def test_region_preserved(self):
+        """The module must not leave the user's computational region changed.
+
+        The module sets the region to its own working resolution. Here a
+        resolution (0.5) different from the current region (res 1) is used, so
+        a module that does not restore the region would leave it at res 0.5.
+        """
+        self.runModule("g.region", n=10, s=0, e=10, w=0, res=1)
+        before = gs.region()
+        self.assertModule(
+            "r.soillossbare",
+            elevation=self.elevation,
+            kfactor=self.kfactor,
+            rfactor=self.rfactor,
+            resolution=0.5,
+            soillossbare=self.output,
+            flowaccmethod="r.watershed",
+            flags="r",
+            overwrite=True,
+        )
+        after = gs.region()
+        self.assertEqual(
+            before,
+            after,
+            msg="r.soillossbare must restore the user's computational region.",
+        )
+
+
+if __name__ == "__main__":
+    test()