Stryker supports a variety of mutators, which are listed below. In parentheses the names of correspondent mutations are specified, which you might need for the ignore-mutations section of the configuration.
Do you have a suggestion for a (new) mutator? Feel free to create an issue!
Arithmetic Operators (arithmetic)​
| Original | Mutated |
|---|
+ | - |
- | + |
* | / |
/ | * |
% | * |
Equality Operators (equality)​
| Original | Mutated |
|---|
> | < |
> | >= |
>= | < |
>= | > |
< | > |
< | <= |
<= | > |
<= | < |
== | != |
!= | == |
is | is not |
is not | is |
Logical Operators (logical)​
| Original | Mutated |
|---|
&& | || |
|| | && |
^ | == |
and | or |
or | and |
Boolean Literals (boolean)​
| Original | Mutated |
|---|
true | false |
false | true |
!person.IsAdult() | person.IsAdult() |
if(person.IsAdult()) | if(!person.IsAdult()) |
while(person.IsAdult()) | while(!person.IsAdult()) |
Assignment Statements (assignment)​
| Original | Mutated |
|---|
+= | -= |
-= | += |
*= | /= |
/= | *= |
%= | *= |
<<= | >>= |
>>= | <<= |
&= | |= |
&= | ^= |
|= | &= |
|= | ^= |
^= | |= |
^= | &= |
??= | = |
Initialization (initializer)​
| Original | Mutated |
|---|
new int[] { 1, 2 }; | new int[] { }; |
int[] numbers = { 1, 2 }; | int[] numbers = { }; |
new List<int> { 1, 2 }; | new List<int> { }; |
new Collection<int> { 1, 2 }; | new Collection<int> { }; |
new Dictionary<int, int> { { 1, 1 } }; | new Dictionary<int, int> { }; |
new SomeClass { Foo = "Bar" }; | new SomeClass { }; |
Removal mutators (statement, block)​
| Original | Mutated |
|---|
void Function() { Age++; } | void Function() {} (block emptied) |
int Function() { Age++; return Age; } | void Function() { return default; } (block emptied) |
return; | removed |
return value; | removed |
break; | removed |
continue; | removed |
goto; | removed |
throw; | removed |
throw exception; | removed |
yield return value; | removed |
yield break; | removed |
MyMethodCall(); | removed |
Unary Operators (unary)​
| Original | Mutated |
|---|
-variable | +variable |
+variable | -variable |
~variable | variable |
Update Operators (update)​
| Original | Mutated |
|---|
variable++ | variable-- |
variable-- | variable++ |
++variable | --variable |
--variable | ++variable |
Checked Statements (checked)​
| Original | Mutated |
|---|
checked(2 + 4) | 2 + 4 |
Linq Methods (linq)​
| Original | Mutated |
|---|
All() | Any() |
Any() | All() |
AsEnumerable() | Reverse() |
Average() | Min() |
Concat() | Except() |
Count() | Sum() |
Except() | Concat() |
First() | FirstOrDefault() |
FirstOrDefault() | First() |
Intersect() | Union() |
IntersectBy() | UnionBy() |
Last() | First() |
Max() | Min() |
MaxBy() | MinBy() |
Min() | Max() |
MinBy() | MaxBy() |
Order() | OrderDescending() |
OrderBy() | OrderByDescending() |
OrderByDescending() | OrderBy() |
OrderDescending() | Order() |
Reverse() | AsEnumerable() |
Single() | SingleOrDefault() |
SingleOrDefault() | Single() |
Skip() | Take() |
SkipLast() | TakeLast() |
SkipWhile() | TakeWhile() |
Sum() | Max() |
Take() | Skip() |
TakeLast() | SkipLast() |
TakeWhile() | SkipWhile() |
ThenBy() | ThenByDescending() |
ThenByDescending() | ThenBy() |
Union() | Intersect() |
UnionBy() | IntersectBy() |
String Literals (string)​
| Original | Mutated |
|---|
"foo" | "" |
"" | "Stryker was here!" |
$"foo {bar}" | $"" |
@"foo" | @"" |
string.Empty | "Stryker was here!" |
string.IsNullOrEmpty(x) | (x != null) |
string.IsNullOrEmpty(x) | (x != "") |
string.IsNullOrWhiteSpace(x) | (x != null) |
string.IsNullOrWhiteSpace(x) | (x != "") |
string.IsNullOrWhiteSpace(x) | (x.Trim() != "") |
String Methods (stringmethod)​
| Original | Mutated |
|---|
ElementAt() | '\0' |
ElementAtOrDefault() | '\0' |
EndsWith() | StartsWith() |
IndexOf() | LastIndexOf() |
LastIndexOf() | IndexOf() |
PadLeft() | PadRight() |
PadRight() | PadLeft() |
StartsWith() | EndsWith() |
Substring() | "" |
ToLower() | ToUpper() |
ToLowerInvariant() | ToUpperInvariant() |
ToUpper() | ToLower() |
ToUpperInvariant() | ToLowerInvariant() |
Trim() | "" |
TrimEnd() | TrimStart() |
TrimStart() | TrimEnd() |
Bitwise Operators (bitwise)​
| Original | Mutated |
|---|
<< | >> |
>> | << |
& | | |
| | & |
a^b | ~(a^b) |
Regular Expressions (regex)​
For the full list of all available regex mutations, see the regex mutator docs.
Math Methods (math)​
| Original | Mutated |
|---|
Acos() | Acosh() |
Acos() | Asin() |
Acos() | Atan() |
Acosh() | Acos() |
Acosh() | Asinh() |
Acosh() | Atanh() |
Asin() | Asinh() |
Asin() | Acos() |
Asin() | Atan() |
Asinh() | Asin() |
Asinh() | Acosh() |
Asinh() | Atanh() |
Atan() | Atanh() |
Atan() | Acos() |
Atan() | Asin() |
Atanh() | Atan() |
Atanh() | Acosh() |
Atanh() | Asinh() |
BitDecrement() | BitIncrement() |
BitIncrement() | BitDecrement() |
Ceiling() | Floor() |
Cos() | Cosh() |
Cos() | Sin() |
Cos() | Tan() |
Cosh() | Cos() |
Cosh() | Sinh() |
Cosh() | Tanh() |
Exp() | Log() |
Floor() | Ceiling() |
Log() | Exp() |
Log() | Pow() |
MaxMagnitude() | MinMagnitude() |
MinMagnitude() | MaxMagnitude() |
Pow() | Log() |
ReciprocalEstimate() | ReciprocalSqrtEstimate() |
ReciprocalSqrtEstimate() | ReciprocalEstimate() |
ReciprocalSqrtEstimate() | Sqrt() |
Sin() | Sinh() |
Sin() | Cos() |
Sin() | Tan() |
Sinh() | Sin() |
Sinh() | Cosh() |
Sinh() | Tanh() |
Tan() | Tanh() |
Tan() | Cos() |
Tan() | Sin() |
Tanh() | Tan() |
Tanh() | Cosh() |
Tanh() | Sinh() |
Null-coalescing Operators (nullcoalescing)​
| Original | Mutated |
|---|
a ?? b | b ?? a |
a ?? b | a |
a ?? b | b |
Conditional Operators (conditional)​
| Original | Mutated |
|---|
x ? a : b | true ? a : b |
x ? a : b | false ? a : b |
Collection Expressions (collectionexpression)​
| Original | Mutated |
|---|
[] | [default] |
[1, 2, 3] | [] |