diff --git a/crates/lang/src/ast.rs b/crates/lang/src/ast.rs
index 93a70889..3afbdd82 100644
--- a/crates/lang/src/ast.rs
+++ b/crates/lang/src/ast.rs
@@ -138,6 +138,8 @@ pub enum Definition<T, Expr, ConstantRecordTag, PackageName> {
     Use(Use<PackageName>),
 
     ModuleConstant(ModuleConstant<T, ConstantRecordTag>),
+
+    Test(Function<T, Expr>),
 }
 
 impl<A, B, C, E> Definition<A, B, C, E> {
@@ -147,7 +149,8 @@ impl<A, B, C, E> Definition<A, B, C, E> {
             | Definition::Use(Use { location, .. })
             | Definition::TypeAlias(TypeAlias { location, .. })
             | Definition::DataType(DataType { location, .. })
-            | Definition::ModuleConstant(ModuleConstant { location, .. }) => *location,
+            | Definition::ModuleConstant(ModuleConstant { location, .. })
+            | Definition::Test(Function { location, .. }) => *location,
         }
     }
 
@@ -157,7 +160,8 @@ impl<A, B, C, E> Definition<A, B, C, E> {
             Definition::Fn(Function { doc, .. })
             | Definition::TypeAlias(TypeAlias { doc, .. })
             | Definition::DataType(DataType { doc, .. })
-            | Definition::ModuleConstant(ModuleConstant { doc, .. }) => {
+            | Definition::ModuleConstant(ModuleConstant { doc, .. })
+            | Definition::Test(Function { doc, .. }) => {
                 let _ = std::mem::replace(doc, Some(new_doc));
             }
         }
diff --git a/crates/lang/src/parser/lexer.rs b/crates/lang/src/parser/lexer.rs
index 1d140384..d845b741 100644
--- a/crates/lang/src/parser/lexer.rs
+++ b/crates/lang/src/parser/lexer.rs
@@ -67,6 +67,7 @@ pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = ParseError> {
         "check" => Token::Assert,
         "const" => Token::Const,
         "fn" => Token::Fn,
+        "test" => Token::Test,
         "if" => Token::If,
         "else" => Token::Else,
         "is" => Token::Is,
diff --git a/crates/lang/src/parser/token.rs b/crates/lang/src/parser/token.rs
index 8faaa339..0811268a 100644
--- a/crates/lang/src/parser/token.rs
+++ b/crates/lang/src/parser/token.rs
@@ -68,6 +68,7 @@ pub enum Token {
     Opaque,
     Pub,
     Use,
+    Test,
     Todo,
     Trace,
     Type,
@@ -145,6 +146,7 @@ impl fmt::Display for Token {
             Token::Todo => "todo",
             Token::Trace => "try",
             Token::Type => "type",
+            Token::Test => "test",
         };
         write!(f, "\"{}\"", s)
     }