Armstrong numbers

typescript/armstrong-numbers/armstrong-numbers.test.ts

@@ -0,0 +1,47 @@
+import { isArmstrongNumber } from './armstrong-numbers'
+
+describe('Armstrong Numbers', () => {
+  it('Single-digit numbers are Armstrong numbers', () => {
+    expect(isArmstrongNumber(5)).toBeTruthy()
+  })
+
+  it('There are no two-digit Armstrong numbers', () => {
+    expect(isArmstrongNumber(10)).toBeFalsy()
+  })
+
+  it('Three-digit number that is an Armstrong number', () => {
+    expect(isArmstrongNumber(153)).toBeTruthy()
+  })
+
+  it('Three-digit number that is not an Armstrong number', () => {
+    expect(isArmstrongNumber(100)).toBeFalsy()
+  })
+
+  it('Four-digit number that is an Armstrong number', () => {
+    expect(isArmstrongNumber(9474)).toBeTruthy()
+  })
+
+  it('Four-digit number that is not an Armstrong number', () => {
+    expect(isArmstrongNumber(9475)).toBeFalsy()
+  })
+
+  it('Seven-digit number that is an Armstrong number', () => {
+    expect(isArmstrongNumber(9926315)).toBeTruthy()
+  })
+
+  it('Seven-digit number that is not an Armstrong number', () => {
+    expect(isArmstrongNumber(9926314)).toBeFalsy()
+  })
+
+  it('Armstrong number containing seven zeroes', () => {
+    expect(
+      isArmstrongNumber(BigInt('186709961001538790100634132976990'))
+    ).toBeTruthy()
+  })
+
+  it('The largest and last Armstrong number', () => {
+    expect(
+      isArmstrongNumber(BigInt('115132219018763992565095597973971522401'))
+    ).toBeTruthy()
+  })
+})