如何在JDK 9 for IntelliJ中向模块添加测试依赖项？

Question

I am building a project with maven 3.3.9 using java 9 (build 9-ea+165). Tests ran and build were successful.

However. IntelliJ Idea 2017.1.2 is complaining and will not compile/run tests with the message 'The module does not have the module 'junit.jupiter.api' in its requirements.

How do I add this for IntelliJ? Is it necessary?

Screenshot:

Project structure:

From pom:

<dependencies>
    <!-- testing -->
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest-all</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-api</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-core</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
<build>
    <pluginManagement>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>9</source>
                    <target>9</target>
                    <showWarnings>true</showWarnings>
                    <showDeprecation>true</showDeprecation>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.19</version>
                <dependencies>
                    <dependency>
                        <groupId>org.junit.platform</groupId>
                        <artifactId>junit-platform-surefire-provider</artifactId>
                        <version>1.0.0-M4</version>
                    </dependency>
                    <dependency>
                        <groupId>org.junit.vintage</groupId>
                        <artifactId>junit-vintage-engine</artifactId>
                        <version>4.12.0-M4</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </pluginManagement>

    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
        </plugin>
        <plugin>
            <artifactId>maven-surefire-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Answer 1

It's possible that your project structure isn't valid anymore. You can try to check if your folder containing your tests is your actual test folder:

1. Press [Ctrl] [Alt] [Shift] [S] to open Project Structure.
2. Open "Modules"
3. Open the "Sources tab"
4. Your folder containing the tests should be marked as "Tests" (the icon will be green)

Answer 2

There are a few options

First, you may not have imported the project correctly into IntelliJ in the first place. In which case the quickest thing to do is often to simply close the project, remove the intellij files from the source directory ( .idea directories and any *.i?l files), and reopen the appropriate root pom file, using the open option (if it gives you the option, choose to create a new project and delete the old project).

Second option is that you have correctly opened the project but you've not reimported it since changing the pom and you don't have autoimport switched on and you ignored the notifications asking you to reload. In which case just open the maven window (usually from a horizontal button on the right of the screen) and hit the reimport button at the top left of the maven window.

The third option is to blow away your caches. This is easily done from the file menu.

There may be others. I'd start from the bottom up.