Added a readme for the test

applications/GeoMechanicsApplication/tests/deactivation_with_structural_element/README.md

@@ -0,0 +1,25 @@
+# Deactivation workflow test with a structural element
+
+This test consists of a single square UPwSmallStrainElement2D4N element with a LinearTrussElement2D2N from the StructuralMechanicsApplication directly attached to the right nodes of the square (no interfaces). It checks the deactivation/activation workflow of the structural element, combined with the `"input_type" : "rest"` option in the second stage.
+
+## Setup
+
+The test is performed in two stages, with the following common conditions for both stages:
+
+- Constraints:
+    - Displacements in the X-direction are all fixed.
+    - Displacements in the X- and Y-direction of the bottom nodes are fixed
+    - The water pressures are fixed to a hydrostatic gradient.
+
+- Material:
+    - The soil material is elastic according to the GeoLinearElasticPlaneStrain2DLaw.
+    - The truss material is described by the TrussConstitutiveLaw.
+
+The following staged analysis is performed:
+- Stage 1: the truss element is deactivated, meaning the water-pressure induced displacement is the same for both top nodes.
+- Stage 2: the truss element is activated and a normal load is applied to the top of the cube. The characteristics of the truss are chosen in such a way that the truss doubles the 'stiffness' of the right side of the cube, yielding half the displacement of the left side.
+
+
+## Assertions
+
+In the first stage, the truss is deactivated, so the expected y displacements are the same for nodes 3 and 4. In the second stage, the truss is activated and since it's only connected to node 4, the displacement of node 4 is half that of node 3 (the stiffness is doubled due to the truss). Therefore, the expected Y displacements for node 3 (left) are 0.05 and -0.1, and for node 4 (right) 0.05 and -0.05 in stage 1 and 2 respectively.

applications/GeoMechanicsApplication/tests/deactivation_with_structural_element/excavation_test_with_structural_elements.mdpa

@@ -18,7 +18,7 @@ Begin Elements LinearTrussElement2D2N// GUI group identifier: truss
 End Elements
 
 Begin Conditions UPwNormalFaceLoadCondition2D2N// GUI group identifier: NormalLoad
-    1 0 4 3
+        1          0     4     3
 End Conditions
 
 Begin SubModelPart BottomFixed // Group BottomFixed // Subtree DISPLACEMENT

applications/GeoMechanicsApplication/tests/test_deactivation_with_structural_element.py

@@ -5,17 +5,15 @@
 import glob
 
 import KratosMultiphysics.GeoMechanicsApplication
-
 from KratosMultiphysics.GeoMechanicsApplication.geomechanics_analysis import GeoMechanicsAnalysis
+
 class KratosGeoMechanicsDeactivationWithStructuralTest(KratosUnittest.TestCase):
     """
     This class contains a test for a multistage computation with deactivation of structural elements in the first stage
+    and the use of 'rest' as input type for the second stage.
     """
 
     def test_deactivation_with_structural_element(self):
-        """
-
-        """
         test_name    = 'deactivation_with_structural_element'
         project_path = test_helper.get_file_path(test_name)