What checks are necessary to verify an interval from 10 to 20?

Interval boundaries: 10 (inclusive) and 20 (inclusive).

Test cases:

• Positive:
  • Minimum value: 10
  • Maximum value: 20
  • Value inside the interval: 15
• Negative:
  • Value less than minimum: 9
  • Value just above maximum: 21
  • Fractional value inside the interval: 10.5 (if fractions are allowed)
  • Fractional value outside the interval: 9.9, 20.1 (if fractions are allowed)
  • Negative value: -5
  • Zero: 0
  • Empty value/null
  • Non-numeric value (string, character)