diff --git a/jest.config.js b/jest.config.js
index 6d422a3..cf6470b 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -2,5 +2,6 @@ module.exports = {
   testEnvironment: "jsdom",
   moduleNameMapper: {
     "\\.(css)$": "<rootDir>/src/__mocks__/styleMock.js",
+    "^wasm-lib$": "<rootDir>/src/__mocks__/wasm-lib.js",
   },
 };
diff --git a/src/__mocks__/wasm-lib.js b/src/__mocks__/wasm-lib.js
new file mode 100644
index 0000000..d8df88f
--- /dev/null
+++ b/src/__mocks__/wasm-lib.js
@@ -0,0 +1,17 @@
+class Vec3 {
+  constructor(x, y, z) {
+    this.x = x;
+    this.y = y;
+    this.z = z;
+  }
+}
+
+class Rgb {
+  constructor(r, g, b) {
+    this.r = r;
+    this.g = g;
+    this.b = b;
+  }
+}
+
+module.exports = { Vec3, Rgb };
diff --git a/src/utils/colour.test.ts b/src/utils/colour.test.ts
new file mode 100644
index 0000000..78f6a0f
--- /dev/null
+++ b/src/utils/colour.test.ts
@@ -0,0 +1,38 @@
+import { rgb, rgbToVec3, vec3ToRGB, RGBToHex } from "./colour";
+import { vec3 } from "./math";
+
+describe("rgb", () => {
+  it("creates an RGB value with the given components", () => {
+    expect(rgb(255, 128, 0)).toEqual({ r: 255, g: 128, b: 0 });
+  });
+});
+
+describe("rgbToVec3", () => {
+  it("converts RGB to a vec3", () => {
+    expect(rgbToVec3(rgb(1, 2, 3))).toEqual(vec3(1, 2, 3));
+  });
+});
+
+describe("vec3ToRGB", () => {
+  it("converts a vec3 to RGB", () => {
+    expect(vec3ToRGB(vec3(1, 2, 3))).toEqual(rgb(1, 2, 3));
+  });
+});
+
+describe("RGBToHex", () => {
+  it("converts black", () => {
+    expect(RGBToHex(rgb(0, 0, 0))).toBe("#000000");
+  });
+
+  it("converts white", () => {
+    expect(RGBToHex(rgb(255, 255, 255))).toBe("#ffffff");
+  });
+
+  it("converts red", () => {
+    expect(RGBToHex(rgb(255, 0, 0))).toBe("#ff0000");
+  });
+
+  it("converts a mixed colour", () => {
+    expect(RGBToHex(rgb(18, 52, 86))).toBe("#123456");
+  });
+});
diff --git a/src/utils/conversions.test.ts b/src/utils/conversions.test.ts
new file mode 100644
index 0000000..c426d31
--- /dev/null
+++ b/src/utils/conversions.test.ts
@@ -0,0 +1,17 @@
+import { wasmVec3, wasmRGB } from "./conversions";
+import { vec3 } from "./math";
+import { rgb } from "./colour";
+
+describe("wasmVec3", () => {
+  it("passes the correct components to the WASM constructor", () => {
+    const result = wasmVec3(vec3(1, 2, 3));
+    expect(result).toMatchObject({ x: 1, y: 2, z: 3 });
+  });
+});
+
+describe("wasmRGB", () => {
+  it("passes the correct components to the WASM constructor", () => {
+    const result = wasmRGB(rgb(255, 128, 0));
+    expect(result).toMatchObject({ r: 255, g: 128, b: 0 });
+  });
+});
diff --git a/src/utils/typeguard.test.ts b/src/utils/typeguard.test.ts
new file mode 100644
index 0000000..b9f3cf6
--- /dev/null
+++ b/src/utils/typeguard.test.ts
@@ -0,0 +1,11 @@
+import { exhaustiveMatchGuard } from "./typeguard";
+
+describe("exhaustiveMatchGuard", () => {
+  it("throws an error with the unexpected value", () => {
+    expect(() => exhaustiveMatchGuard("unexpected" as never)).toThrow("Unexpected value");
+  });
+
+  it("includes the value in the error message", () => {
+    expect(() => exhaustiveMatchGuard({ foo: "bar" } as never)).toThrow(JSON.stringify({ foo: "bar" }));
+  });
+});