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TemperatureConvertorTest.cls

@isTest
public class TemperatureConvertorTest {

    @isTest static void testWarmTemp()
    {
        Decimal celsius=TemperatureConvertor.FahrenheitToCelsius(70);
        System.assertEquals(21.11, celsius);
    }
    
    @isTest static void testFreezingPoint()
    {
        Decimal celsius=TemperatureConvertor.FahrenheitToCelsius(32);
        System.assertEquals(0,celsius);
    }
    
    @isTest static void testBoilingPoint()
    {
         Decimal celsius=TemperatureConvertor.FahrenheitToCelsius(212);
        System.assertEquals(100,celsius,'Boiling point temperature is not expected ');
        
    }
      
     @isTest static void testNegativeTemp()
    {
        Decimal celsius=TemperatureConvertor.FahrenheitToCelsius(-10);
        System.assertEquals(-23.33,celsius);
    }
}