1 files changed, 51 insertions, 0 deletions
diff --git a/packages/math/range.test.ts b/packages/math/range.test.ts
new file mode 100644
index 0000000..fb4b6a3
--- /dev/null
+++ b/packages/math/range.test.ts
@@ -0,0 +1,51 @@
+import { rangeInclusive, rangeIntersection, rangesOverlap } from "./range";
+
+describe("range overlap", () => {
+  const range1_4 = rangeInclusive(1, 4);
+
+  it("should overlap when range a contains range b", () => {
+    expect(rangesOverlap(range1_4, rangeInclusive(2, 3))).toBe(true);
+    expect(rangesOverlap(range1_4, range1_4)).toBe(true);
+    expect(rangesOverlap(range1_4, rangeInclusive(1, 3))).toBe(true);
+    expect(rangesOverlap(range1_4, rangeInclusive(2, 4))).toBe(true);
+  });
+
+  it("should overlap when range b contains range a", () => {
+    expect(rangesOverlap(rangeInclusive(2, 3), range1_4)).toBe(true);
+    expect(rangesOverlap(rangeInclusive(1, 3), range1_4)).toBe(true);
+    expect(rangesOverlap(rangeInclusive(2, 4), range1_4)).toBe(true);
+  });
+
+  it("should overlap when range a and b intersect", () => {
+    expect(rangesOverlap(range1_4, rangeInclusive(2, 5))).toBe(true);
+  });
+});
+
+describe("range intersection", () => {
+  const range1_4 = rangeInclusive(1, 4);
+
+  it("should intersect completely with itself", () => {
+    expect(rangeIntersection(range1_4, range1_4)).toEqual(range1_4);
+  });
+
+  it("should intersect irrespective of order", () => {
+    expect(rangeIntersection(range1_4, rangeInclusive(2, 3))).toEqual([2, 3]);
+    expect(rangeIntersection(rangeInclusive(2, 3), range1_4)).toEqual([2, 3]);
+    expect(rangeIntersection(range1_4, rangeInclusive(3, 5))).toEqual(
+      rangeInclusive(3, 4),
+    );
+    expect(rangeIntersection(rangeInclusive(3, 5), range1_4)).toEqual(
+      rangeInclusive(3, 4),
+    );
+  });
+
+  it("should intersect at the edge", () => {
+    expect(rangeIntersection(range1_4, rangeInclusive(4, 5))).toEqual(
+      rangeInclusive(4, 4),
+    );
+  });
+
+  it("should not intersect", () => {
+    expect(rangeIntersection(range1_4, rangeInclusive(5, 7))).toEqual(null);
+  });
+});