library(testthat)

describe("temperature()", {
  it("generates output", {
    expect_match(temperature("celcius", 0), "273.15 kelvin or 32 farenheit")
    expect_match(temperature("c", 100), "373.15 kelvin or 212 farenheit")

    # Fahrenheit to Celsius and Kelvin
    expect_match(temperature("farenheit", 32), "0 celcius or 273.15 kelvin")
    expect_match(temperature("f", 212), "100 celcius or 373.15 kelvin")

    # Kelvin to Celsius and Fahrenheit
    expect_match(temperature("kelvin", 273.15), "0 celcius or 32 farenheit")
    expect_match(temperature("k", 373.15), "100 celcius or 212 farenheit")
  })

  it("handles edge cases", {
    # Absolute zero in Celsius should convert correctly
    expect_match(temperature("c", -273.15), "0 kelvin or -459.67 farenheit")

    # Absolute zero in Fahrenheit should convert correctly
    expect_match(temperature("f", -459.67), "-273.15 celcius or 0 kelvin")

    # Absolute zero in Kelvin should convert correctly
    expect_match(temperature("k", 0), "-273.15 celcius or -459.67 farenheit")
  })

  it("generates error when input is invalid", {
    # Test for NA value
    expect_error(temperature("c", NA), "Input is NA")

    # Test for non-numeric input
    expect_error(temperature("c", "thirty"), "Enter numeric input")

    # Test for invalid unit input
    expect_error(temperature("invalid_unit", 100), "Enter valid input")
  })
})