The following is comment written for a C function:GATE:2011

The following is comment written for a C function:
/* This function computes the roots of a quadratic equation  a.x^2+b.x+c=0. The function stores two real roots in *root1 and *root2 and returns the status of validity of roots. It handles four different kinds of cases.
(i)When coefficient a is zero irrespective of discriminant
(ii) When discriminant is positive
(iii) When discrimanant is zero
(iv) When discrimanant is negative
Only in cases (ii) and (iii) , the stored roots are valid.Otherwise 0 is stored in the roots. the function returns 0 when
the roots are valid and -1 otherwise.
The function also ensures root1 >= root2.
int get_QuadRoots float a, float b, float c,()float *root1, float *root2 ;
*\

Software test engineer is assigned the job of doing black box testing. He comes up with the following test cases, many of which are redundant.

TEST SET INPUT SET EXPECTED OUTPUT SET
T no. a b c root1 root2 return value
T1 0.0 0.0 7.0 0.0 0.0 -1
T2 0.0 1.0 3.0 0.0 0.0 -1
T3 1.0 2.0 1.0 --1.0 -1.0 0
T4 4.0 -12.0 9.0 1.5 1.5 0
T5 1.0 -2.0 -3.0 3.0 -1.0 0
T6 1.0 1.0 4.0 0.0 0.0 -1

Which one of the following options provide the set of non-redundant tests using equivalence class partitioning approach from input perspective for black box testing?

(A) T1,T2,T3,T6                 (B) T1,T3,T4,T5                 (C) T2,T4,T5,T6                 (D) T2,T3,T4,T5

ANSWER :(C)

EXPLANATION:

T1 AND T2

hence, anyone of T1 AND Tis redundant.

T3 AND T4  ,in both case discriminant (D) = \({b^2-4ac}\)=0 

 

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