What are some common (or worthwhile) tests, test questions, weaknesses, or misunderstandings dealing with numeric inputs?
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For example, here are a couple sample ideas:
- I commonly see users enter text into number fields (eg, ">4" or "4 days", etc).
- Fields left blank (null)
- Very long numeric strings
- Multiple decimals and commas (eg, "4..4" and "4,,434.4.4")
- Boundary Value Analysis:
- Lower Boundary
- Lower Boundary - 1 (for decimal/float, use smaller amounts)
- Upper Boundary
- Upper Boundary + 1
- Far below the lower boundary (eg, beyond the hardware boundary value)
- Far above the upper boundary
- middle of the range
- 0
- 0.0
- White space, nothing else " "
- String input
- Number with text in front or back, eg "$5.00", "4 lbs", "about 60", "50+"
- Negative numbers
- + sign with positive numbers, "+4"
- Both plus and minus sign, eg "+-4" and "-4e+30"
- Exponents of 10, both uppercase and lowercase, positive and negative eg "4e10", "-5E-10", "+6e+60", etc
- Too many "e" characters, eg "4e4e4" "4EE4"
- Impossibly large/small exponents or inappropriate ones
- Decimal values that cannot be represented in a computer
- eg, .3 + .6 == 1.0? This bug affects most hardware, so outputs that compare decimal values should allow for a degree of error.
- Integer/hardware overflow. Eg, for 32-bit integers, what happens when adding 4 billion to 4 billion? *