Clean up tests

tests/test_exercises/exercises/compilation_failure.rs

@@ -0,0 +1,3 @@
+fn main() {
+    let
+}

tests/test_exercises/exercises/compilation_success.rs

@@ -0,0 +1 @@
+fn main() {}

tests/test_exercises/exercises/not_in_info.rs

@@ -0,0 +1 @@
+fn main() {}

tests/test_exercises/exercises/test_failure.rs

@@ -0,0 +1,9 @@
+fn main() {}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn fails() {
+        asset!(false);
+    }
+}

tests/test_exercises/exercises/test_success.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("Output from `main` function");
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn passes() {}
+}