diff --git a/tests/diff.rs b/tests/diff.rs
index 4a6c4bd..4200bb6 100644
--- a/tests/diff.rs
+++ b/tests/diff.rs
@@ -74,21 +74,47 @@ fn run_diff_test<F: FnOnce(&[u8]) -> Vec<u8>>(test_dir: &str, name: &str, test:
 	}
 }
 
-macro_rules! def_stack_height_test {
-	( $name:ident ) => {
-		#[test]
-		fn $name() {
-			run_diff_test("stack-height", concat!(stringify!($name), ".wat"), |input| {
-				let module = elements::deserialize_buffer(input).expect("Failed to deserialize");
-				let instrumented = utils::stack_height::inject_limiter(module, 1024).expect("Failed to instrument with stack counter");
-				elements::serialize(instrumented).expect("Failed to serialize")
-			});
-		}
-	};
+mod stack_height {
+	use super::*;
+
+	macro_rules! def_stack_height_test {
+		( $name:ident ) => {
+			#[test]
+			fn $name() {
+				run_diff_test("stack-height", concat!(stringify!($name), ".wat"), |input| {
+					let module = elements::deserialize_buffer(input).expect("Failed to deserialize");
+					let instrumented = utils::stack_height::inject_limiter(module, 1024).expect("Failed to instrument with stack counter");
+					elements::serialize(instrumented).expect("Failed to serialize")
+				});
+			}
+		};
+	}
+
+	def_stack_height_test!(simple);
+	def_stack_height_test!(start);
+	def_stack_height_test!(table);
+	def_stack_height_test!(global);
+	def_stack_height_test!(imports);
 }
 
-def_stack_height_test!(simple);
-def_stack_height_test!(start);
-def_stack_height_test!(table);
-def_stack_height_test!(global);
-def_stack_height_test!(imports);
+mod gas {
+	use super::*;
+
+	macro_rules! def_gas_test {
+		( $name:ident ) => {
+			#[test]
+			fn $name() {
+				run_diff_test("gas", concat!(stringify!($name), ".wat"), |input| {
+					let rules = utils::rules::Set::default();
+
+					let module = elements::deserialize_buffer(input).expect("Failed to deserialize");
+					let instrumented = utils::inject_gas_counter(module, &rules).expect("Failed to instrument with gas metering");
+					elements::serialize(instrumented).expect("Failed to serialize")
+				});
+			}
+		};
+	}
+
+	def_gas_test!(simple);
+	def_gas_test!(start);
+}
diff --git a/tests/expectations/gas/simple.wat b/tests/expectations/gas/simple.wat
new file mode 100644
index 0000000..d23ec7c
--- /dev/null
+++ b/tests/expectations/gas/simple.wat
@@ -0,0 +1,26 @@
+(module
+  (type (;0;) (func))
+  (type (;1;) (func (param i32)))
+  (import "env" "gas" (func (;0;) (type 1)))
+  (func (;1;) (type 0)
+    i32.const 3
+    call 0
+    i32.const 1
+    if  ;; label = @1
+      i32.const 2
+      call 0
+      loop  ;; label = @2
+        i32.const 3
+        call 0
+        i32.const 123
+        drop
+      end
+    end)
+  (func (;2;) (type 0)
+    i32.const 2
+    call 0
+    block  ;; label = @1
+      i32.const 1
+      call 0
+    end)
+  (export "simple" (func 1)))
diff --git a/tests/expectations/gas/start.wat b/tests/expectations/gas/start.wat
new file mode 100644
index 0000000..89f43b5
--- /dev/null
+++ b/tests/expectations/gas/start.wat
@@ -0,0 +1,20 @@
+(module
+  (type (;0;) (func (param i32 i32)))
+  (type (;1;) (func))
+  (type (;2;) (func (param i32)))
+  (import "env" "ext_return" (func (;0;) (type 0)))
+  (import "env" "memory" (memory (;0;) 1 1))
+  (import "env" "gas" (func (;1;) (type 2)))
+  (func (;2;) (type 1)
+    i32.const 5
+    call 1
+    i32.const 8
+    i32.const 4
+    call 0
+    unreachable)
+  (func (;3;) (type 1)
+    i32.const 1
+    call 1)
+  (export "call" (func 3))
+  (start 2)
+  (data (i32.const 8) "\01\02\03\04"))
diff --git a/tests/fixtures/gas/simple.wat b/tests/fixtures/gas/simple.wat
new file mode 100644
index 0000000..cee2b6b
--- /dev/null
+++ b/tests/fixtures/gas/simple.wat
@@ -0,0 +1,15 @@
+(module
+	(func (export "simple")
+		(if (i32.const 1)
+			(loop
+				i32.const 123
+				drop
+			)
+		)
+	)
+
+	(func
+		block
+		end
+	)
+)
diff --git a/tests/fixtures/gas/start.wat b/tests/fixtures/gas/start.wat
new file mode 100644
index 0000000..0ae1a0f
--- /dev/null
+++ b/tests/fixtures/gas/start.wat
@@ -0,0 +1,18 @@
+(module
+	(import "env" "ext_return" (func $ext_return (param i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+	(start $start)
+	(func $start
+		(call $ext_return
+			(i32.const 8)
+			(i32.const 4)
+		)
+		(unreachable)
+	)
+
+	(func (export "call")
+	)
+
+	(data (i32.const 8) "\01\02\03\04")
+)