add an e2e test for iterator ordering

examples/variable-ordering.stur

@@ -0,0 +1,5 @@
+symbols: N, M
+iters: covar -> i, j, k, iter
+covar(j, k) := X(i, j) * X(i, k) * (0 < iter <= 1000)
+covar:D(i, j) := (0 <= i < N) * (0 <= j < N)
+X:D(i, j) := (0 <= i < M) * (0 <= j < N)

src/test/resources/correct_test_outputs/variable-ordering_wo_body.cpp

@@ -0,0 +1,45 @@
+
+#include <iostream>
+#include <random>
+#include <algorithm>
+#include <chrono>
+
+using namespace std;
+using namespace std::chrono;
+
+extern "C"
+void fn(double ** covar, double ** X, int N, int M) {
+
+
+long time_computation = 0, start_computation, end_computation;
+start_computation = duration_cast<microseconds>(system_clock::now().time_since_epoch()).count();
+for (int i = 0; i < M; ++i) {
+
+for (int j = 0; j < N; ++j) {
+
+for (int k = 0; k < min({(j) + 1, N}); ++k) {
+
+
+covar[j][k] += (X[i][k] * X[i][j]);
+}
+}
+}
+end_computation = duration_cast<microseconds>(system_clock::now().time_since_epoch()).count();
+time_computation = end_computation - start_computation;
+cout << time_computation << endl;
+long time_reconstruction = 0, start_reconstruction, end_reconstruction;
+start_reconstruction = duration_cast<microseconds>(system_clock::now().time_since_epoch()).count();
+for (int j = 0; j < N; ++j) {
+
+int kp = j;
+for (int k = max({(j) + 1, 0}); k < N; ++k) {
+
+int jp = k;
+covar[j][k] = covar[jp][kp];
+}
+}
+end_reconstruction = duration_cast<microseconds>(system_clock::now().time_since_epoch()).count();
+time_reconstruction = end_reconstruction - start_reconstruction;
+cout << time_reconstruction << endl;
+
+}

src/test/scala/uk/ac/ed/dal/structtensor/codegen/CodegenTest.scala

@@ -2130,4 +2130,26 @@ class CodegenTest extends AnyFlatSpec with Matchers {
     val lines2 = file2.getLines().toList
     lines2 should be(lines1)
   }
+
+  it should "generate code with variable ordering without the body" in {
+    Utils.cnt = 0
+    Main.main(
+      Array(
+        "-i",
+        "examples/variable-ordering.stur",
+        "-o",
+        "src/test/resources/test_outputs/variable-ordering_wo_body_test.cpp"
+      )
+    )
+
+    val file1 = scala.io.Source.fromFile(
+      "src/test/resources/correct_test_outputs/variable-ordering_wo_body.cpp"
+    )
+    val file2 = scala.io.Source.fromFile(
+      "src/test/resources/test_outputs/variable-ordering_wo_body_test.cpp"
+    )
+    val lines1 = file1.getLines().toList
+    val lines2 = file2.getLines().toList
+    lines2 should be(lines1)
+  }
 }