Maven artifact scopes revisited

In a prior post about when to use which scope for a Maven artifact, I left out the provided scope, because, as I said at the time, “I don’t get as confused about that one so I left it out.” I spoke too soon.  : )

When I said that, I was only thinking of which classpath(s) the artifact would available to in its immediate project.  But there are two additional concerns besides the classpath availability: whether the artifact will be built into the resulting (.war) target, and whether artifacts depending on this one will inherit the dependency.  The latter issue is also affected by the <optional> tag.

The following table reflects my current understanding of how the scope and optionalness of a dependency affect:

• The classpath(s) in which the artifact is available;
• Whether the artifact is included in the war; and
• When artifact A declares a dependency on artifact D: whether artifacts declaring a dependency on artifact A will also transitively get a dependency on artifact D.

Scope	Optional?	Classpaths in which artifact is available			Artifact included in war**	Dependency propagates transitively
		(main) compile	(main) runtime	test*
compile	No	X	X	X	X	X
compile	Yes	X	X	X	X
runtime	No		X	X*	X	X
runtime	Yes		X	X*	X
test	No			X	?	X
test	Yes			X	?
provided	No		X	X
provided	Yes		X	X
system	No		X	X
system	Yes		X	X

*Note that the “test” classpath is used both at test compile time and test runtime; it doesn’t seem to  be possible to specify that an artifact should be available at test runtime but not test compile time.

**I don’t think it has to necessarily be packaged as war… trying to make a concrete example.