dependencyManagement and scope

A little late to the party, but I'll add my two cents.

I recently ran into a very difficult to debug issue.
I have a parent pom for managing dependencies across multiple projects. I had it set with all the dependencies common amongst them and included groupId, artifactId, version and the most common scope.
My thinking would be that I would not have to include scope in the actual dependency section in each project if it fell in line with that most common scope.
The problem occurred when some of those dependencies showed up as transitive dependencies. For example, if:

A depends on B at compile scope.

B depends on C at compile scope.

C is set to provided in dependencyManagement of parent.

Then A's transitive dependency on C is determined to be provided. I'm not really sure if that makes sense or not, but it certainly is confusing.

Anyway, save yourself the hassle, and leave scope out of your dependencyManagement.

dependencyManagement is just here to define dependencies version for all project submodules, the only pertinent scope in this section is import for BOMs.

Scope must be defined in dependencies section.

(For a given dependency it determines the usage context. It allows to include the dependency only when it is required for execution. For example an ear will not be packaged with Java-ee dependencies (scope provided) as it will find them on the target server.)

[edit]

The first statement has an exception, the scope provided in dependencyManagement section will override defined scope in dependencies sections. see DependencyManagement to force scope

As with other answers, best practice is to exclude scope from dependencyManagement and explicitly specify it when defining the dependency. It is a rare case that you would want a different version of the same dependency in different scopes, e.g., one version when compiling your app and a different when running it -- the only case I can think of is you want to explicitly run your tests against a different version of a library in case users use that version instead of the one you specify.

If you define scope in dependencyManagement, it restricts the use of that version to ONLY the defined scope -- so any other scopes will pick up a random version of the dependency. I ran into this yesterday when we had defined junit 4.12 in dependencyManagement with test scope, but our common test framework module used junit with compile scope, so it picked up version 4.8.2 instead.

There is no gain in adding a single dependency to the dependency management, for any scope. All you have is the duplication. If you want to have the version configurable, add a property and use it in your dependency:

<properties>
        <junit.version>4.10</junit.version> 
    ...
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
    </dependency>
</dependencies>

However, there are cases where the dependency management shines - when you are using boms in order to orchestrate the versions for a larger collections of artifacts, like using a certain version of a Java EE implementation:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.jboss.bom</groupId>
            <artifactId>jboss-javaee-6.0-with-tools</artifactId>
            <version>${javaee6.with.tools.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
....