g.region: fix setting from default region (#2397)

Fix after g.region was broken with #1627 (78d902d). Added test for d flag.

general/g.region/main.c

@@ -425,7 +425,9 @@ int main(int argc, char *argv[])
 	print_flag |= PRINT_REG;
     }
 
-    if (!flag.dflt->answer)
+    if (flag.dflt->answer)
+	update_file = true;
+    else
 	G_get_window(&window);
 
     /* region= */

general/g.region/testsuite/test_g_region.py

@@ -0,0 +1,47 @@
+"""Test of g.region
+
+@author Anna Petrasova
+"""
+from grass.gunittest.case import TestCase
+import grass.script as gs
+
+
+class TestRegion(TestCase):
+    @classmethod
+    def setUpClass(cls):
+        """Use temporary region settings"""
+        cls.use_temp_region()
+
+    @classmethod
+    def tearDownClass(cls):
+        """!Remove the temporary region"""
+        cls.del_temp_region()
+
+    def test_d_flag(self):
+        n = 228500
+        res = 1
+        n_default = 320000
+        res_default = 500
+
+        self.runModule("g.region", res=res, n=n)
+        region = gs.region()
+        self.assertEqual(n, region["n"])
+        self.assertEqual(res, region["nsres"])
+
+        # test default with no update flag
+        self.runModule("g.region", flags="dup")
+        region = gs.region()
+        self.assertEqual(n, region["n"])
+        self.assertEqual(res, region["nsres"])
+
+        # test set default
+        self.runModule("g.region", flags="d")
+        region = gs.region()
+        self.assertEqual(n_default, region["n"])
+        self.assertEqual(res_default, region["nsres"])
+
+
+if __name__ == "__main__":
+    from grass.gunittest.main import test
+
+    test()