nixosTests.fenics: Add basic test

nixos/tests/fenics.nix

@@ -0,0 +1,50 @@
+import ./make-test-python.nix ({ pkgs, ... }:
+
+let
+  fenicsScript = pkgs.writeScript "poisson.py" ''
+    #!/usr/bin/env python
+    from dolfin import *
+
+    mesh = UnitSquareMesh(4, 4)
+    V = FunctionSpace(mesh, "Lagrange", 1)
+
+    def boundary(x):
+        return x[0] < DOLFIN_EPS or x[0] > 1.0 - DOLFIN_EPS
+
+    u0 = Constant(0.0)
+    bc = DirichletBC(V, u0, boundary)
+
+    u = TrialFunction(V)
+    v = TestFunction(V)
+    f = Expression("10*exp(-(pow(x[0] - 0.5, 2) + pow(x[1] - 0.5, 2)) / 0.02)", degree=2)
+    g = Expression("sin(5*x[0])", degree=2)
+    a = inner(grad(u), grad(v))*dx
+    L = f*v*dx + g*v*ds
+
+    u = Function(V)
+    solve(a == L, u, bc)
+    print(u)
+  '';
+in
+{
+  name = "fenics";
+  meta = {
+    maintainers = with pkgs.stdenv.lib.maintainers; [ knedlsepp ];
+  };
+
+  nodes = {
+    fenicsnode = { pkgs, ... }: {
+      environment.systemPackages = with pkgs; [
+        gcc
+        (python3.withPackages (ps: with ps; [ fenics ]))
+      ];
+      virtualisation.memorySize = 512;
+    };
+  };
+  testScript =
+    { nodes, ... }:
+    ''
+      start_all()
+      node1.succeed("${fenicsScript}")
+    '';
+})