diff --git a/src/main.test.ts b/src/main.test.ts
index 3c4805f..89dc514 100644
--- a/src/main.test.ts
+++ b/src/main.test.ts
@@ -1,7 +1,7 @@
 import * as fs from "node:fs/promises";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
-import { main, resetErrors } from "./main.js";
+import { main, maybeParseAsExpression, resetErrors } from "./main.js";
 import { mockError, mockExit, mockLog } from "./test-utils.js";
 
 vi.mock("node:fs/promises");
@@ -61,4 +61,55 @@ describe("main", () => {
 			"Operands must be two numbers or two strings.\n[line 1]",
 		);
 	});
+
+	describe("maybeParseAsExpression", () => {
+		it("should parse an expressions", () => {
+			const error = mockError();
+			expect(maybeParseAsExpression("1 + 2*2")).toMatchInlineSnapshot(`
+				{
+				  "kind": "binary",
+				  "left": {
+				    "kind": "literal",
+				    "value": 1,
+				  },
+				  "operator": {
+				    "lexeme": "+",
+				    "line": 1,
+				    "literal": null,
+				    "type": "+",
+				  },
+				  "right": {
+				    "kind": "binary",
+				    "left": {
+				      "kind": "literal",
+				      "value": 2,
+				    },
+				    "operator": {
+				      "lexeme": "*",
+				      "line": 1,
+				      "literal": null,
+				      "type": "*",
+				    },
+				    "right": {
+				      "kind": "literal",
+				      "value": 2,
+				    },
+				  },
+				}
+			`);
+			expect(error).not.toHaveBeenCalled();
+		});
+
+		it("should return null and not log on a statement", () => {
+			const error = mockError();
+			expect(maybeParseAsExpression("1 + 2*2;")).toBeNull();
+			expect(error).not.toHaveBeenCalled();
+		});
+
+		it("should return null and not log on a syntax error", () => {
+			const error = mockError();
+			expect(maybeParseAsExpression("1 + 2*")).toBeNull();
+			expect(error).not.toHaveBeenCalled();
+		});
+	});
 });
diff --git a/src/main.ts b/src/main.ts
index 717b585..9e50cd1 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -55,7 +55,7 @@ let throwMode = false;
 
 class ParseError extends Error {}
 
-function maybeParseAsExpression(line: string): Expr | null {
+export function maybeParseAsExpression(line: string): Expr | null {
 	throwMode = true;
 	try {
 		const scanner = new Scanner(line + ";");