Add initial IGA test

This first mesh file has no sidesets, so we'll do a transient solve, to
get a decent run with only Neumann BCs.

Refs idaholab#18768

test/tests/meshgenerators/file_mesh_generator/2d_diffusion_iga.i

@@ -0,0 +1,46 @@
+[Mesh]
+  [cyl2d_iga]
+    type = FileMeshGenerator
+    file = PressurizedCyl_Patch6_4Elem.e
+  []
+[]
+
+[Variables]
+  [u]
+    order = SECOND  # Must match mesh order
+    family = RATIONAL_BERNSTEIN
+  []
+[]
+
+[Kernels]
+  [time]
+    type = TimeDerivative
+    variable = u
+    block = 0  # Avoid direct calculations on spline nodes
+  []
+  [diff]
+    type = Diffusion
+    variable = u
+    block = 0  # Avoid direct calculations on spline nodes
+  []
+  [null]
+    type = NullKernel
+    variable = u
+    block = 1  # Keep kernel coverage check happy
+  []
+[]
+
+[ICs]
+  [u]
+    type = FunctionIC
+    variable = u
+    function = 'sin(x)'
+  []
+[]
+
+[Executioner]
+  type = Transient
+  num_steps = 2
+  solve_type = NEWTON
+  dtmin = 1
+[]

test/tests/meshgenerators/file_mesh_generator/tests

@@ -22,6 +22,18 @@
     issues = '#14916'
   [../]
 
+  [./exodus_iga_test]
+    type = 'RunApp'
+    input = '2d_diffusion_iga.i'
+    expect_out = 'Solve Converged'
+    recover = false
+    exodus_version = '>=8.0'
+
+    requirement = 'The system shall have the ability to read IsoGeometric Analysis meshes in ExodusII format.'
+    design = 'meshgenerators/FileMeshGenerator.md'
+    issues = '#18768'
+  []
+
   [./pre_checkpoint_load_test]
     type = 'RunApp'
     input = '2d_diffusion_test.i'