diff --git a/tests/unit/transform-axis-mapping.test.ts b/tests/unit/transform-axis-mapping.test.ts
new file mode 100644
index 00000000..2a401c20
--- /dev/null
+++ b/tests/unit/transform-axis-mapping.test.ts
@@ -0,0 +1,53 @@
+import { describe, expect, it } from "vitest";
+
+import { resolveDominantLocalAxisForWorldAxis } from "../../src/viewport-three/transform-axis-mapping";
+
+describe("transform axis mapping", () => {
+  it("maps a world axis onto the dominant local axis for rotated targets", () => {
+    expect(
+      resolveDominantLocalAxisForWorldAxis(
+        {
+          x: 0,
+          y: 90,
+          z: 0
+        },
+        "x"
+      )
+    ).toBe("z");
+
+    expect(
+      resolveDominantLocalAxisForWorldAxis(
+        {
+          x: 90,
+          y: 0,
+          z: 0
+        },
+        "y"
+      )
+    ).toBe("z");
+  });
+
+  it("keeps the same axis when the target is not rotated", () => {
+    expect(
+      resolveDominantLocalAxisForWorldAxis(
+        {
+          x: 0,
+          y: 0,
+          z: 0
+        },
+        "x"
+      )
+    ).toBe("x");
+
+    expect(
+      resolveDominantLocalAxisForWorldAxis(
+        {
+          x: 0,
+          y: 0,
+          z: 0
+        },
+        "z"
+      )
+    ).toBe("z");
+  });
+});