library(testthat)

describe("Length()",{
  it("can show valid conversions", {
    expect_output(Length("mm", "cm", 100), "100 mm = 10 cm")
    expect_output(Length("cm", "m", 200), "200 cm = 2 m")
    expect_output(Length("cm", "mm", 5), "5 cm = 50 mm")
    expect_output(Length("m", "cm", 3), "3 m = 0.03 cm")
    expect_output(Length("mm", "m", 1000), "1000 mm = 1 m")
    expect_output(Length("m", "mm", 1.5), "1.5 m = 1500 mm")
  })

  it("can handle edge cases", {
  # zero inputs
    expect_output(Length("mm", "cm", 0), "0 mm = 0 cm")
    expect_output(Length("m", "cm", 0), "0 m = 0 cm")

  # large input values
    expect_output(Length("mm", "m", 1000000), "1000 m")
  })
})