diff --git a/tests/gs_test.cpp b/tests/gs_test.cpp
index e9a50b4..a129307 100644
--- a/tests/gs_test.cpp
+++ b/tests/gs_test.cpp
@@ -1,38 +1,45 @@
 #include "gs/gs.h"
 #include <gtest/gtest.h>
 
-TEST(GSTests, CountElementsAboveThreshold) {
-    double threshold = 0.5;
-    double count = countElementsAboveThreshold(threshold);
-    ASSERT_GE(count, 0.0);
-    ASSERT_LE(count, 1.0);
+// Test 0.1: Check that the type of the model parameters (F, k) matches that of the element type of the u and v vectors.
+TEST(GSTests, CheckParameterTypes) {
+    // Check if types of F and k match the type of elements in u and v
+    ASSERT_TRUE((std::is_same<decltype(F), double>::value));
+    ASSERT_TRUE((std::is_same<decltype(k), double>::value));
+    using UElementType = decltype(u[0][0]);
+    using VElementType = decltype(v[0][0]);
+    ASSERT_TRUE(typeid(F).name() == typeid(UElementType).name() && typeid(k).name() == typeid(VElementType).name());
+    // std::cout << "Test1 Passed!" << std::endl;
 }
 
-TEST(GSTests, GridInitializationTest) {
-
-    const int width = 256;
-    const int height = 256;
-
-    init();
+// Test 0.2: Check that the variables u and v are the same size.
+TEST(GSTests, CheckSameSize) {
+    // Check if u and v have the same dimensions
+    EXPECT_EQ(u.size(), v.size());
+    for (size_t i = 0; i < u.size(); ++i) {
+        EXPECT_EQ(u[i].size(), v[i].size());
+    }
+}
 
-    for (int x = 0; x < width; ++x) {
-        for (int y = 0; y < height; ++y) {
-            EXPECT_EQ(u[x][y], 1.0);
+// Test 0.3: Check that the simulation produces the mathematically correct answer when u = 0 and v = 0.
+TEST(GSTests, writeVTKFile) {
+    for (auto &row : u)
+        std::fill(row.begin(), row.end(), 0.0);
+    for (auto &row : v)
+        std::fill(row.begin(), row.end(), 0.0);
 
-            if (x >= 100 && x <= 200 && y >= 100 && y <= 150){
-                EXPECT_GE(v[x][y], 0.0); 
-                EXPECT_LE(v[x][y], 1.0); 
-            }
-            else {
-                EXPECT_EQ(v[x][y], 0.0);
-            }
+    simulateStep();
+    for (size_t x = 1; x < width - 1; ++x) {
+        for (size_t y = 1; y < height - 1; ++y) {
+            // When both u and v are 0, the result should stay 0 (assuming no external feed or kill rates)
+            EXPECT_DOUBLE_EQ(0.0018, u[x][y]);
+            EXPECT_DOUBLE_EQ(0.0, v[x][y]);
         }
     }
+    std::cout << "Simulation check successful: u increases to 0.0018 and v remains at 0." << std::endl;
 }
 
-TEST(GSTests, writeVTKFile) {
-    // Your code here, modify the following lines
-    int iteration = 0;
-    writeVTKFile(iteration);
-    EXPECT_EQ(1.0, 1.0);
-}
+int main(int argc, char **argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
\ No newline at end of file