add constructor assertions for ClassAssert

[xenoterracide]

Example

assertThat(MyClass.class).hasPackageOrBetterNoArgConstructor(); // common for frameworks
assertThat(MyClass.class).hasPublicConstructor(Integer.class, String.class); // common for published api's

I'm not fussy on names

[joel-costigliola]

I would likely split hasPackageOrBetterNoArgConstructor into hasPackage and hasPackagePrivateConstructor and add hasProtectedConstructor

[xenoterracide]

that's probably fine, hmm could have hasBeanConstructor, but yeah if you prefer splitting it I'm ok with that.

[wettera]

Does this issue mean that we need to test whether a class have a private or protected or public constructor? I want to fix this issue
For example:
assertThat(MyClass.class).hasPrivateConstructor
assertThat(MyClass.class).hasProtectedConstructor
assertThat(MyClass.class).hasPublicConstructor
@xenoterracide @joel-costigliola

[wettera]

sorry......
forget the brackets and semicolon after each asseration.

[scordio]

Thinking out loud, would it make sense to introduce assertions for java.lang.reflect.Constructor?

And AbstractClassAssert would have a new getConstructor(Class<?>...) method.

Something like:

assertThat(MyClass.class).getConstructor()  // default constructor
                         .isPublic();
assertThat(MyClass.class).getConstructor(Integer.class, String.class)
                         .isPackagePrivate();

[wettera]

But one class could have multiple constructors, these constructors may be private, protected, or public.

[wettera]

.getConstructor() may get a constructor list. Maybe in the list one constructor is parvate, another contructor is public.

[scordio]

But one class could have multiple constructors, these constructors may be private, protected, or public.

The getConstructor(Class<?>...) I proposed would have Class#getDeclaredConstructor(Class<?>...) behind, where the resulting constructor depends on the parameter types given as input, so only one constructor at a time would be returned.

This is actually a second step. It would be enough to have ConstructorAssert which provides assertions on the modifiers. Something like this could be written:

assertThat(MyClass.class.getDeclaredConstructor()).isPublic();

[wettera]

But one class could have multiple constructors, these constructors may be private, protected, or public.

The getConstructor(Class<?>...) I proposed would have Class#getDeclaredConstructor(Class<?>...) behind, where the resulting constructor depends on the parameter types given as input, so only one constructor at a time would be returned.

This is actually a second step. It would be enough to have ConstructorAssert which provides assertions on the modifiers. Something like this could be written:

assertThat(MyClass.class.getDeclaredConstructor()).isPublic();

Both MyClass.class.getDeclaredConstructors() and MyClass.class.getConstructors() parameter list is empty. I checked just now.

[wettera]

But one class could have multiple constructors, these constructors may be private, protected, or public.

The getConstructor(Class<?>...) I proposed would have Class#getDeclaredConstructor(Class<?>...) behind, where the resulting constructor depends on the parameter types given as input, so only one constructor at a time would be returned.

This is actually a second step. It would be enough to have ConstructorAssert which provides assertions on the modifiers. Something like this could be written:

assertThat(MyClass.class.getDeclaredConstructor()).isPublic();

Sorry I make a mistake, instance.getClass().getDeclaredConstructors() and instance.getClass().getConstructors() parameter list is empty.

[wettera]

But one class could have multiple constructors, these constructors may be private, protected, or public.

The getConstructor(Class<?>...) I proposed would have Class#getDeclaredConstructor(Class<?>...) behind, where the resulting constructor depends on the parameter types given as input, so only one constructor at a time would be returned.

This is actually a second step. It would be enough to have ConstructorAssert which provides assertions on the modifiers. Something like this could be written:

assertThat(MyClass.class.getDeclaredConstructor()).isPublic();

Sorry.....
MyClass.class.getDeclaredConstructors()
MyClass.class.getConstructors()
instance.getClass().getDeclaredConstructors()
instance.getClass().getDeclaredConstructors()
can have parameter type as input and return one unique constructor.
I'm sorry I was so careless.

[scordio]

@xenoterracide @wettera we discussed the topic internally and we would prefer a separate ConstructorAssert to avoid bloating the ClassAssert API. Do you see any issue with it?

[xenoterracide]

nope, though you might consider allowing chaining from the class assert, that way it's easily discoverable, but I'll leave that up to you. Since my biggest priority was to ensure that I had a public noargs constructor.

[scordio]

you might consider allowing chaining from the class assert

Yes, chaining is definitely in the roadmap

[JitendraProgrammer]

Hi Guys,

Can you guide me how can i contribute here