diff --git a/tests/functions.rs b/tests/functions.rs
new file mode 100644
index 0000000..710862d
--- /dev/null
+++ b/tests/functions.rs
@@ -0,0 +1,143 @@
+use dust_lang::*;
+
+#[test]
+fn function_call() {
+    assert_eq!(
+        interpret(
+            "
+                foobar = (message <str>) <str> { message }
+                foobar('Hiya')
+                ",
+        ),
+        Ok(Value::string("Hiya".to_string()))
+    );
+}
+
+#[test]
+fn call_empty_function() {
+    assert_eq!(
+        interpret(
+            "
+                foobar = (message <str>) <none> {}
+                foobar('Hiya')
+                ",
+        ),
+        Ok(Value::none())
+    );
+}
+
+#[test]
+fn callback() {
+    assert_eq!(
+        interpret(
+            "
+            foobar = (cb <() -> str>) <str> {
+                cb()
+            }
+            foobar(() <str> { 'Hiya' })
+            ",
+        ),
+        Ok(Value::string("Hiya".to_string()))
+    );
+}
+
+#[test]
+fn built_in_function_call() {
+    assert_eq!(interpret("output('Hiya')"), Ok(Value::Option(None)));
+}
+
+#[test]
+fn function_context_does_not_capture_normal_values() {
+    assert_eq!(
+        interpret(
+            "
+            x = 1
+
+            foo = () <any> { x }
+            "
+        ),
+        Err(Error::VariableIdentifierNotFound("x".to_string()))
+    );
+}
+
+#[test]
+fn function_context_captures_functions() {
+    assert_eq!(
+        interpret(
+            "
+            x = 1
+            foo = (x <int>) <int> { x }
+            foo(2)
+            "
+        ),
+        Ok(Value::Integer(2))
+    );
+
+    assert_eq!(
+        interpret(
+            "
+            bar = () <int> { 2 }
+            foo = () <int> { bar() }
+            foo()
+            "
+        ),
+        Ok(Value::Integer(2))
+    );
+
+    assert_eq!(
+        interpret(
+            "
+            foo = () <int> { bar() }
+            foo()
+            bar = () <int> { 2 }
+            "
+        ),
+        Ok(Value::Integer(2))
+    );
+}
+
+#[test]
+fn function_context_captures_structure_definitions() {
+    let map = Map::new();
+
+    map.set("name".to_string(), Value::string("bob"), None)
+        .unwrap();
+
+    assert_eq!(
+        interpret(
+            "
+            User = struct {
+                name <str>
+            }
+            
+            bob = () <User> {
+                new User {
+                    name = 'bob'
+                }
+            }
+
+            bob()
+            "
+        ),
+        Ok(Value::Map(map.clone()))
+    );
+
+    assert_eq!(
+        interpret(
+            "
+            bob = () <User> {
+                new User {
+                    name = 'bob'
+                }
+            }
+
+            User = struct {
+                name <str>
+            }
+            
+            bob()
+            "
+        ),
+        Ok(Value::Map(map))
+    );
+}
diff --git a/tests/interpret.rs b/tests/interpret.rs
index cb7514c..087ce30 100644
--- a/tests/interpret.rs
+++ b/tests/interpret.rs
@@ -1,3 +1,5 @@
+mod functions;
+
 mod structure {
     use std::collections::BTreeMap;
 
@@ -233,56 +235,6 @@ mod value {
     }
 }
 
-mod function_call {
-    use dust_lang::*;
-
-    #[test]
-    fn function_call() {
-        assert_eq!(
-            interpret(
-                "
-                foobar = (message <str>) <str> { message }
-                foobar('Hiya')
-                ",
-            ),
-            Ok(Value::string("Hiya".to_string()))
-        );
-    }
-
-    #[test]
-    fn call_empty_function() {
-        assert_eq!(
-            interpret(
-                "
-                foobar = (message <str>) <none> {}
-                foobar('Hiya')
-                ",
-            ),
-            Ok(Value::none())
-        );
-    }
-
-    #[test]
-    fn callback() {
-        assert_eq!(
-            interpret(
-                "
-                foobar = (cb <() -> str>) <str> {
-                    cb()
-                }
-                foobar(() <str> { 'Hiya' })
-                ",
-            ),
-            Ok(Value::string("Hiya".to_string()))
-        );
-    }
-
-    #[test]
-    fn built_in_function_call() {
-        assert_eq!(interpret("output('Hiya')"), Ok(Value::Option(None)));
-    }
-}
-
 mod if_else {
     use dust_lang::*;