diff --git a/kalk/src/interpreter.rs b/kalk/src/interpreter.rs
index 1ad54eb..f5330b8 100644
--- a/kalk/src/interpreter.rs
+++ b/kalk/src/interpreter.rs
@@ -235,3 +235,56 @@ fn eval_fn_call_expr(
         _ => Err(format!("Undefined function: '{}'.", identifier)),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::lexer::TokenKind::*;
+    use crate::test_helpers::*;
+
+    const PRECISION: u32 = 53;
+
+    fn interpret(stmt: Stmt) -> Result<Option<Float>, String> {
+        let mut symbol_table = SymbolTable::new();
+        let mut context = Context::new(&mut symbol_table, &Unit::Radians, PRECISION);
+        context.interpret(vec![stmt])
+    }
+
+    #[test]
+    fn test_literal() {
+        let stmt = Stmt::Expr(literal("1"));
+
+        assert_eq!(
+            interpret(stmt).unwrap().unwrap(),
+            Float::with_val(PRECISION, 1)
+        );
+    }
+
+    #[test]
+    fn test_binary() {
+        let add = Stmt::Expr(binary(literal("2"), Plus, literal("3")));
+        let sub = Stmt::Expr(binary(literal("2"), Minus, literal("3")));
+        let mul = Stmt::Expr(binary(literal("2"), Star, literal("3")));
+        let div = Stmt::Expr(binary(literal("2"), Slash, literal("4")));
+        let pow = Stmt::Expr(binary(literal("2"), Power, literal("3")));
+
+        assert_eq!(interpret(add).unwrap().unwrap(), 5);
+        assert_eq!(interpret(sub).unwrap().unwrap(), -1);
+        assert_eq!(interpret(mul).unwrap().unwrap(), 6);
+        assert_eq!(interpret(div).unwrap().unwrap(), 0.5);
+        assert_eq!(interpret(pow).unwrap().unwrap(), 8);
+    }
+
+    #[test]
+    fn test_unary() {
+        let neg = Stmt::Expr(unary(Minus, literal("1")));
+        let fact = Stmt::Expr(unary(Exclamation, literal("5")));
+        let fact_dec = Stmt::Expr(unary(Exclamation, literal("5.2")));
+
+        assert_eq!(interpret(neg).unwrap().unwrap(), -1);
+        assert_eq!(interpret(fact).unwrap().unwrap(), 120);
+
+        let fact_dec_result = interpret(fact_dec).unwrap().unwrap();
+        assert!(fact_dec_result > 169.406 && fact_dec_result < 169.407);
+    }
+}
diff --git a/kalk/src/lib.rs b/kalk/src/lib.rs
index 27362af..ed5fbe9 100644
--- a/kalk/src/lib.rs
+++ b/kalk/src/lib.rs
@@ -4,3 +4,4 @@ mod lexer;
 pub mod parser;
 mod prelude;
 mod symbol_table;
+mod test_helpers;
diff --git a/kalk/src/parser.rs b/kalk/src/parser.rs
index 47f6f89..d4fb686 100644
--- a/kalk/src/parser.rs
+++ b/kalk/src/parser.rs
@@ -310,6 +310,7 @@ fn is_at_end(context: &mut Context) -> bool {
 mod tests {
     use super::*;
     use crate::lexer::{Token, TokenKind::*};
+    use crate::test_helpers::*;
     use test_case::test_case;
 
     fn parse_with_context(context: &mut Context, tokens: Vec<Token>) -> Result<Stmt, String> {
@@ -325,33 +326,6 @@ mod tests {
         parse_stmt(&mut context)
     }
 
-    fn token(kind: TokenKind, value: &str) -> Token {
-        Token {
-            kind,
-            value: value.into(),
-        }
-    }
-
-    fn literal(value: &str) -> Box<Expr> {
-        Box::new(Expr::Literal(value.into()))
-    }
-
-    fn var(identifier: &str) -> Box<Expr> {
-        Box::new(Expr::Var(identifier.into()))
-    }
-
-    fn binary(left: Box<Expr>, op: TokenKind, right: Box<Expr>) -> Box<Expr> {
-        Box::new(Expr::Binary(left, op, right))
-    }
-
-    fn unary(op: TokenKind, expr: Box<Expr>) -> Box<Expr> {
-        Box::new(Expr::Unary(op, expr))
-    }
-
-    fn group(expr: Box<Expr>) -> Box<Expr> {
-        Box::new(Expr::Group(expr))
-    }
-
     #[test]
     fn test_var() {
         // x
diff --git a/kalk/src/test_helpers.rs b/kalk/src/test_helpers.rs
new file mode 100644
index 0000000..0b1101c
--- /dev/null
+++ b/kalk/src/test_helpers.rs
@@ -0,0 +1,31 @@
+#![allow(dead_code)]
+use crate::ast::Expr;
+use crate::lexer::Token;
+use crate::lexer::TokenKind;
+
+pub fn token(kind: TokenKind, value: &str) -> Token {
+    Token {
+        kind,
+        value: value.into(),
+    }
+}
+
+pub fn literal(value: &str) -> Box<Expr> {
+    Box::new(Expr::Literal(value.into()))
+}
+
+pub fn var(identifier: &str) -> Box<Expr> {
+    Box::new(Expr::Var(identifier.into()))
+}
+
+pub fn binary(left: Box<Expr>, op: TokenKind, right: Box<Expr>) -> Box<Expr> {
+    Box::new(Expr::Binary(left, op, right))
+}
+
+pub fn unary(op: TokenKind, expr: Box<Expr>) -> Box<Expr> {
+    Box::new(Expr::Unary(op, expr))
+}
+
+pub fn group(expr: Box<Expr>) -> Box<Expr> {
+    Box::new(Expr::Group(expr))
+}