Additional test for membrane macro

Author: Ladme

src/system/groups.rs

@@ -1391,6 +1391,20 @@ mod tests {
         }
     }
 
+    #[test]
+    fn group_create_macro_membrane_cdl() {
+        let mut system = System::from_file("test_files/lipids_cdl.gro").unwrap();
+
+        system.group_create("Membrane", "@membrane").unwrap();
+
+        assert!(system.group_exists("Membrane"));
+        assert_eq!(system.group_get_n_atoms("Membrane").unwrap(), 10);
+
+        for i in 5..=14 {
+            assert!(system.group_isin("Membrane", i).unwrap());
+        }
+    }
+
     #[test]
     fn group_create_macro_water() {
         let mut system = System::from_file("test_files/example.gro").unwrap();

test_files/lipids_cdl.gro

@@ -0,0 +1,22 @@
+Some lipids
+19
+   91GLU      N    1   6.922   9.769   2.710 -1.1275  0.9916 -0.3234
+   91GLU    HT1    2   6.896   9.839   2.783  0.4496 -0.3359  1.6217
+   91GLU    HT2    3   6.847   9.697   2.717  1.1326 -1.3695  1.8055
+  254HSD      N    4   8.989   7.897   4.156 -0.4872 -0.2891  0.0639
+  254HSD     HN    5   9.052   7.919   4.231  0.6136  0.2378 -0.9856
+  273POPG   H8R    6   9.233   7.062   3.760 -1.0711  0.6524 -1.6746
+  273POPG   H8S    7   9.156   7.218   3.740 -1.7546  0.8697  2.6281
+  468POPE   C36    8   7.245   4.640   4.326  0.3764 -0.4239 -0.1301
+  468POPE   H6X    9   7.238   4.749   4.303 -0.1457  0.2098  2.6621
+  468POPE   H6Y   10   7.139   4.616   4.351  0.7463 -1.4734  0.4694
+  468POPE   C37   11   7.275   4.569   4.199 -0.9834  0.1166 -0.3320
+  468POPE   H7X   12   7.242   4.463   4.203 -0.7496  0.0656  0.6113
+  999PVCL2   C3   13   6.161   3.649   5.655  0.5465  0.0085 -0.2735
+  999PVCL2 HG31   14   6.219   3.574   5.598  1.1382 -0.0297  0.3582
+  999PVCL2 HG32   15   6.119   3.590   5.739  1.8662 -0.2091  0.2686
+ 1421SOD    SOD   16  15.185  15.449   5.172 -0.5434  0.4421  0.4209
+ 1516CLA    CLA   17  11.419  16.319   0.906 -0.0201  0.4162  0.1013
+ 1578TIP3    H1   18  11.748   5.034   0.595  1.0741  0.1692  1.3002
+ 1578TIP3    H2   19  11.890   5.033   0.542  0.7238 -1.8443  0.3331
+  16.47191  16.47191   7.48299