feat(utilities): add min helper function

This will provide a curried function to calculate the min value of two parameters. This should be
replaced by ramda as soon as their types have been fixed.

Close DCOS-38496

Author: Poltergeist

packages/utilities/components/min.ts

@@ -0,0 +1,17 @@
+function calculate(a, b) {
+  return b < a ? b : a;
+}
+
+function min(a?: number | Date | string, b?: number | Date | string) {
+  if (arguments.length === 0) {
+    return min;
+  }
+  if (arguments.length === 1) {
+    return b => {
+      return calculate(a, b);
+    };
+  }
+  return calculate(a, b);
+}
+
+export default min;

packages/utilities/index.ts

@@ -0,0 +1 @@
+export { default as min } from "./components/min";

packages/utilities/tests/min.test.ts

@@ -0,0 +1,33 @@
+import { default as min } from "../components/min";
+
+describe("min", () => {
+  it("returns the smaller of its two arguments", () => {
+    expect(min(-7, 7)).toEqual(-7);
+    expect(min(7, -7)).toEqual(-7);
+  });
+
+  it("works for any orderable type", () => {
+    var d1 = new Date("2001-01-01");
+    var d2 = new Date("2002-02-02");
+
+    expect(min(d1, d2)).toEqual(d1);
+    expect(min(d2, d1)).toEqual(d1);
+    expect(min("a", "b")).toEqual("a");
+    expect(min("b", "a")).toEqual("a");
+  });
+  it("returns is a function", () => {
+    expect(typeof min).toBe("function");
+  });
+
+  it("returns a function after adding the min value", () => {
+    expect(typeof min(1)).toBe("function");
+  });
+
+  it("is returning the min value", () => {
+    expect(min(1)(10)).toBe(1);
+  });
+
+  it("is returning the lower value value", () => {
+    expect(min(12)(10)).toBe(10);
+  });
+});