Software Testing and Analysis: Process, Principles and Techniques 1st Edition

10.3 Identify independently testable units in the following specification.

Desk calculator Desk calculator performs the following algebraic operations: sum, subtraction, product, division, and percentage on integers and real numbers. Operands must be of the same type, except for percentage, which allows the first operator to be either integer or real, but requires the second to be an integer that indicates the percentage to be computed. Operations on integers produce integer results. Program Calculator can be used with a textual interface that provides the following commands:

Mx=N, where Mx is a memory location, that is, M0 M9, and N is a number. Integers are given as nonempty sequences of digits, with or without sign. Real numbers are given as nonempty sequences of digits that include a dot ".", with or without sign. Real numbers can be terminated with an optional exponent, that is, character "E" followed by an integer. The command displays the stored number.

Mx=display, where Mx is a memory location and display indicates the value shown on the last line.

operand1 operation operand2, where operand1 and operand2 are numbers or memory locations or display and operation is one of the following symbols: "+", "-", "*", "/", "%", where each symbol indicates a particular operation. Operands must follow the type conventions. The command displays the result or the string Error.

2 456the 10 digits , 11, the operations , El to display the result of a sequence of operations to clear display M, LA MRL McIl where MS C, whereM is pressed before a digit to indicate the target is pressed before a digit to indicate the target memory, O...9, keysMMS MC, pressed after M and a digit indicate the operation to be performed on the target memory: add display to memory, store display in memory, retrieve memory, that is, move the value in memory to the display and clear memory Example DO M3 MRprints 65 (the value 15 is stored in memory cell 3 and then retrieved to compute 80 15). G1SDL (Specification Description Language) is a formal specification notation based on extended finite state machines, widely used in telecommunication systems and standardized by the International Telecommunication Union. 2 456the 10 digits , 11, the operations , El to display the result of a sequence of operations to clear display M, LA MRL McIl where MS C, whereM is pressed before a digit to indicate the target is pressed before a digit to indicate the target memory, O...9, keysMMS MC, pressed after M and a digit indicate the operation to be performed on the target memory: add display to memory, store display in memory, retrieve memory, that is, move the value in memory to the display and clear memory Example DO M3 MRprints 65 (the value 15 is stored in memory cell 3 and then retrieved to compute 80 15). G1SDL (Specification Description Language) is a formal specification notation based on extended finite state machines, widely used in telecommunication systems and standardized by the International Telecommunication Union