diff --git a/src/lib.rs b/src/lib.rs
index 37bfe92..4c80049 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,3 +6,5 @@ pub use fem::
     is_points_of_quadrilateral_on_the_same_plane, convex_hull_on_four_points_on_plane,
     ElementForceComponent,
 };
+
+mod tests;
diff --git a/src/tests/fem/mod.rs b/src/tests/fem/mod.rs
new file mode 100644
index 0000000..931ea15
--- /dev/null
+++ b/src/tests/fem/mod.rs
@@ -0,0 +1 @@
+mod test_fem;
diff --git a/src/tests/fem/test_fem.rs b/src/tests/fem/test_fem.rs
new file mode 100644
index 0000000..df733ac
--- /dev/null
+++ b/src/tests/fem/test_fem.rs
@@ -0,0 +1,71 @@
+#![allow(unused_imports)]
+
+use crate::fem::{FEM, DOFParameter, ElementForceComponent};
+
+
+#[test]
+fn test_integration_simple() -> Result<(), String>
+{
+    const REL_TOL: f32 = 1e-4;
+    const ABS_TOL: f32 = 1e-12;
+
+    let mut model = FEM::create(REL_TOL, ABS_TOL, 2);
+
+    model.add_node(1, 0.0, 0.0, 0.0)?;
+    model.add_node(2, 30.0, 0.0, 0.0)?;
+
+    model.add_truss(1, 1, 2, 1e6, 2.0, None)?;
+
+    model.add_displacement(1, DOFParameter::X, 0.0)?;
+
+    model.add_concentrated_load(2, DOFParameter::X, 100.0)?;
+
+    let separated_stiffness_matrix = model.separate_stiffness_matrix()?;
+    let r_a_vector = model.compose_r_a_vector(separated_stiffness_matrix.get_k_aa_indexes())?;
+    let u_b_vector = model.compose_u_b_vector(separated_stiffness_matrix.get_k_bb_indexes())?;
+
+    let u_a_vector = model.find_ua_vector(
+        &separated_stiffness_matrix, &r_a_vector, &u_b_vector,
+    )?;
+    let r_r_vector = model.find_r_r_vector(
+        &separated_stiffness_matrix, &u_a_vector, &u_b_vector,
+    )?;
+
+    model.compose_global_analysis_result(
+        separated_stiffness_matrix.get_k_aa_indexes(), 
+        separated_stiffness_matrix.get_k_bb_indexes(), 
+        &u_a_vector,
+        &r_r_vector,
+    )?;
+
+    let mut global_analysis_result = model.extract_global_analysis_result()?;
+
+    global_analysis_result.sort_by(
+        |(n_1, dof_1, _, _), (n_2, dof_2, _, _)| 
+        (n_1, dof_1).partial_cmp(&(n_2, dof_2)).unwrap()
+    );
+    let global_analysis_result_expected = vec![
+        (1, DOFParameter::X, 0.0, -100.0),
+        (1, DOFParameter::Y, 0.0, 0.0),
+        (1, DOFParameter::Z, 0.0, 0.0),
+        (1, DOFParameter::ThX, 0.0, 0.0),
+        (1, DOFParameter::ThY, 0.0, 0.0),
+        (1, DOFParameter::ThZ, 0.0, 0.0),
+        (2, DOFParameter::X, 0.0014999999, 100.0),
+        (2, DOFParameter::Y, 0.0, 0.0),
+        (2, DOFParameter::Z, 0.0, 0.0),
+        (2, DOFParameter::ThX, 0.0, 0.0),
+        (2, DOFParameter::ThY, 0.0, 0.0),
+        (2, DOFParameter::ThZ, 0.0, 0.0),
+    ];
+
+    let elements_analysis_result = model.extract_elements_analysis_result()?;
+    let elements_analysis_result_expected = vec![
+        (1, vec![(ElementForceComponent::ForceR, 100.0)]),
+    ];
+
+    assert_eq!(global_analysis_result, global_analysis_result_expected);
+    assert_eq!(elements_analysis_result, elements_analysis_result_expected);
+
+    Ok(())
+}
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
new file mode 100644
index 0000000..24a3768
--- /dev/null
+++ b/src/tests/mod.rs
@@ -0,0 +1 @@
+mod fem;
\ No newline at end of file