What is the use of eq() argument matcher if passing the string directly will do the same thing.
e.g. the behaviour of
when(method.foo("test")).thenReturn("bar");
is similar to
when(method.foo(ArgumentMatcher.eq("test"))).thenReturn("bar");
There are more ArgumentMatchers than eq(). Another popular one is any(), but there are many more ArgumentMatchers. They are generally used together to help identify the correct value for the test case. You may not want to check all args in all tests. For example, if there were more params in your code.
when(method.foo(eq("test"), any(Test.class), isNull()).thenReturn("bar");
I agree that eq() seems redundant, but the trick is if one argument uses a matcher all must, so if you want to use one any() you can no longer just put an unwrapped String argument.
Related
I was creating a function and I tried to increase the value of the parameter which was declared as Integer. But it said that the value of that parameter can not be reassigned. I am a beginner so if I am missing some concept please tell me.
Yes, in Kotlin function parameters can't be changed.
(However, if they refer to mutable objects, then those objects can change. For example, if you declared fun a(b: List<String>), then you could add another String to the List; but you couldn't set b to refer to a different List.)
This is different from Java, where parameters are variable (unless specified as final).
This behaviour was announced in Kotlin milestone M5.1, where it was explained as avoiding confusion (especially in constructors), and promoting good style.
See also this answer.
I am new to Mockito and trying to cover following source code:
jdbcOperations.update(insertRoleQuery,new Object[]{"menuName","subMenuName","subSubMenuName","aa","bb","cc","role"});
In this query is taking 7 string parameters. I have written the mockito test case for the code and it's also covering the source code but I am not sure whether it's the correct way or not.
when(jdbcOperations.update(Mockito.anyString(), new Object[]{Mockito.anyString(),Mockito.anyString(),Mockito.anyString(),Mockito.anyString(),Mockito.anyString(),Mockito.anyString(),Mockito.anyString()})).thenThrow(runtimeException);
Please suggest if i am doing it right way or not.
Thanks
As per the docs, you can either use exact values, or argument matchers, but not both at the same time:
Warning on argument matchers:
If you are using argument matchers, all arguments have to be provided
by matchers.
If you do mix them, like in your sample, mockito will complain with something similar to
org.mockito.exceptions.misusing.InvalidUseOfMatchersException:
Invalid use of argument matchers!
2 matchers expected, 1 recorded:
-> at MyTest.shouldMatchArray(MyTest.java:38)
This exception may occur if matchers are combined with raw values:
//incorrect:
someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
//correct:
someMethod(anyObject(), eq("String by matcher"));
For more info see javadoc for Matchers class.
In your case you don't seem to care about the array contents, so you can just use any():
when(jdbcOperation.update(anyString(), any())).thenThrow(runtimeException);
If you want to at least check the number of parameters, you can use either
org.mockito.Mockito's argThat(argumentMatcher):
when(jdbcOperation.update(anyString(), argThat(array -> array.length == 7))).thenThrow(runtimeException);
org.mockito.hamcrest.MockitoHamcrest's argThat(hamcrestMatcher):
when(jdbcOperation.update(anyString(), argThat(arrayWithSize(7)))).thenThrow(runtimeException);
If you're interested in matching certain values, you can use AdditionalMatchers.aryEq(expectedArray), or just Mockito.eq(expectedArray) which has a special implementation for arrays, but I fell that the first one expresses your intent in a clearer way.
when(jdbcOperation.update(anyString(), aryEq(new Object[]{"whatever"}))).thenThrow(runtimeException);
I was looking at some code of a fellow developer, and almost cried. In the method definition there are 12 arguments. From my experience..this isn't good. If it were me, I would have sent in an object of some sort.
Is there another / more preferred way to do this (in other words, what's the best way to fix this and explain why)?
public long Save (
String today,
String name,
String desc,
int ID,
String otherNm,
DateTime dt,
int status,
String periodID,
String otherDt,
String submittedDt
)
ignore my poor variable names - they are examples
It highly depends on the language.
In a language without compile-time typechecking (e.g. python, javascript, etc.) you should use keyword arguments (common in python: you can access them like a dictionary passed in as an argument) or objects/dictionaries you manually pass in as arguments (common in javascript).
However the "argument hell" you described is sometimes "the right way to do things" for certain languages with compile-time typechecking, because using objects will obfuscate the semantics from the typechecker. The solution then would be to use a better language with compile-time typechecking which allows pattern-matching of objects as arguments.
Yes, use objects. Also, the function is probably doing too much if it needs all of this information, so use smaller functions.
Use objects.
class User { ... }
User user = ...
Save(user);
It decision provides easy way for adding new parameters.
It depends on how complex the function is. If it does something non-trivial with each of those arguments, it should probably be split. If it just passes them through, they should probably be collected in an object. But if it just creates a row in a table, it's not really big deal. It's less of a deal if your language supports keyword arguments.
I imagine the issue you're experiencing is being able to look at the method call and know what argument is receiving what value. This is a pernicious problem in a language like Java, which lacks something like keyword arguments or JSON hashes to pass named arguments.
In this situation, the Builder pattern is a useful solution. It's more objects, three total, but leads to more comprehensible code for the problem you're describing. So the three objects in this case would be as such:
Thing: stateful entity, typically immutable (i.e. getters only)
ThingBuilder: factory class, creates a Thing entity and sets its values.
ThingDAO: not necessary for using the Builder pattern, but addresses your question.
Interaction
/*
ThingBuilder is a static inner class of Thing, where each of its
"set" method calls returns the ThingBuilder instance being worked with
while the final "build()" call returns the instantiated Thing instance.
*/
Thing thing = Thing.createBuilder().
.setToday("2012/04/01")
.setName("Example")
// ...etc...
.build();
// the Thing instance as get methods for each property
thing.getName();
// get your reference to thingDAO however it's done
thingDAO.save(thing);
The result is you get named arguments and an immutable instance.
Let's say I have a method, Foo(). There are only certain times when Foo() is appropriate, as determined by the method ShouldFooNow(). However, there are many times when the program must consider if Foo() is appropriate at this time. So instead of writing:
if ShouldFooNow():
Foo()
everywhere, I just make that into one function:
def __name():
if ShouldFooNow():
Foo()
What would be a good name for this method? I'm having a hard time coming up with a good convention. IfNecessaryFoo() is awkward, particularly if Foo() has a longer name. DoFooIfShould()? Even more awkward.
What would be a better name style?
I think you're pretty close. Put the action/intent at the head of the method name, for easier alphabetic searching. If I were writing something like that, I'd consider
FooIfNecessary()
FooIfRequired()
Say, for instance,
ElevatePermissionsIfNecessary()
You could use EnsureFoo().
For example, the method EnsurePermissions() will take the appropriate action if needed. If the permissions are already correct, the method won't do anything.
I've recently started using the convention:
FooIf(args, bool);
Where args are any arguments that the method takes and bool is either expecting a boolean value or a Func of some kind that resolves to a boolean. Then, within that method, I check the bool and run the logic. Keeps such assertions down to one line and looks clean to me.
Example in my C# code for logging:
public void WarnIf<T>(T value, string message, Func<T, bool> isTrue)
{
if (isTrue(value)) _log.Warn(message);
}
Then I would call it with something like:
WarnIf(someObject, "This is a warning message to be logged.", s => s.SomeCondition == true);
(That caller may not be correct, but you get the idea... I don't have the code in front of me right now.)
Michael Petrotta's answer (IfNecessary or IfRequired suffix) is good, but I prefer a shorter alternative: IfNeeded.
ElevatePermissionsIfNeeded()
And if you want something even shorter I would consider a prefix like May or Might:
MayElevatePermissions()
MightElevatePermissions()
I don't see what's wrong with the original code:
if shouldFoo():
Foo();
is perfectly clear IMHO.
Not just that, but it clearly separates concerns of deciding about doing the action, vs the action itself.
Another option for a similar question with a slightly different approach to avoiding the postfix:
https://softwareengineering.stackexchange.com/a/161754/262009
For example, suppose I this:
class Gundam00 extends Gundam implements MobileSuit {
...
public void fight(final List<MobileSuit> mobiruSuitso, final List<Gundam> theOtherDudes, final List<Person> casualities) {
....
}
}
Suppose theOtherDudes and casualities parameters are optional. How can I make this method as clean as possible? I thought about having booleans indicating if they're null, and then checking them as needed.
I could also have different versions of the method for each combination of parameters but there would be a lot of code duplication I think.
Any suggestions?
I find that past 2-3 arguments, the ability to remember what all the arguments to a function are suffers. And comprehensibility along with it.
Passing named arguments can help. Languages with a convenient hash-like literal syntax make this really easy. Take JavaScript:
g = new Gundam00();
g.fight({opponent: enemy, casualties: 'numerous'});
You can also take advantage of variable length argument features to work this in (treat odd arguments as names, even arguments as the actual parameters).
g.fight('opponent',enemy,'casualties', 'numerous');
And some languages actually support named arguments straight-out (see: http://en.wikipedia.org/wiki/Named_parameter#Use_in_programming_languages ).
Finally, you might want to consider adding other methods for this using what some call a Fluent Interface (http://en.wikipedia.org/wiki/Fluent_interface ). Basically, you've got method call which return the object itself, so you can chain calls together:
g.opponent(enemy).casualties('numerous').fight();
This might be the easiest option if you're working in a manifestly/statically-typed class-focused language.
Update
Responding to Setsuna's comment... in that last example, if you've got the luxury, you can make methods like opponent and casualties simple setters that don't affect any internal state or computation in any other way than setting a parameter for which they're named. They simply set internal properties up, and then all of the real work happens inside action methods like fight.
If you can't do that (or if you don't like writing methods whose operations are sub-atomic), you could stake out a half-way spot between this idea with the hash-like literal idea, and create your own collection class specifically for invoking named arguments:
n = new NArgs();
g.fight(n.arg('opponent',enemy).arg('casualties','numerous').arg('motion','slow'));
A little more unwieldy, but it separates out the named arguments problem and lets you keep your methods a bit more atomic, and NArgs is probably something you could implement pretty easily just wrapping some methods around one type of Collection (HashTable?) or another that's available in your language.
Add the methods. Overloading methods is generally an antipattern and a refactoring opportunity for someone else.
http://www.codinghorror.com/blog/2007/03/curlys-law-do-one-thing.html
I thought about having booleans indicating if they're null, and then checking them inside and reacting accordingly.
Or ... you could just check if they're null.
if(theOtherDudes == null)
...
If there is only one "main method" in your class, then you can implement the optional arguments as getter/setter functions. Example:
public void setOtherDudes(final List<Gundam> theOtherDudes) {} // for input arguments
public List<Person> getCasualities() {} // for output arguments
And then, in your documentation, mention that if the caller has any optional input arguments it has to be passed in before calling fight(), and the optional output values will be available when fight() has been called.
This is worthwhile if there are dozens of optional arguments. Otherwise, I suggest overloading the method as the simplest way.