JarCastingscalafix-maven-plugin
scalafix-maven-plugin enables automatic refactoring and linting of Maven projects written in Scala using Scalafix.
Installation
Add plugin into plugins node of pom.xml:
<plugins>
<plugin>
<groupId>io.github.evis</groupId>
<artifactId>scalafix-maven-plugin</artifactId>
<version>0.1.4_0.9.23</version>
</plugin>
</plugins>
Where 0.1.4 is version of the plugin itself, and 0.9.23 is version of Scalafix invoked by the plugin.
Then, you need to setup a file .scalafix.conf in the root directory of your Maven project (note the dot at the start of filename). You can find .scalafix.conf guide here.
In order to execute semantic rules (e.g., RemoveUnused), you need to enable SemanticDB compiler plugin too:
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>${scala-maven-plugin.version}</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
<configuration>
<args>
<arg>-Ywarn-unused</arg> <!-- if you need exactly RemoveUnused -->
</args>
<compilerPlugins>
<compilerPlugin>
<groupId>org.scalameta</groupId>
<artifactId>semanticdb-scalac_${scala.version}</artifactId>
<version>${semanticdb.version}</version>
</compilerPlugin>
</compilerPlugins>
</configuration>
</plugin>
You don't need to care about passing Scala version and Scalac options to this plugin specifically. Plugin finds them automatically from your build info.
By default, sources should be located inside src/main/scala directory. Though, you may change it using sourceDirectory configuration option, e.g.:
<plugin>
<groupId>io.github.evis</groupId>
<artifactId>scalafix-maven-plugin</artifactId>
<version>0.1.4_0.9.23</version>
<configuration>
<sourceDirectory>src/main/my-sources-dir</sourceDirectory>
</configuration>
</plugin>
Usage
There is one Maven goal in this plugin called scalafix:scalafix. It executes Scalafix with given config on your sources.
First of all, you can invoke it via CLI:
mvn scalafix:scalafix
If there are some errors while running Scalafix, then the build will fail. Otherwise, it will succeed.
In order to execute semantic rules (e.g., RemoveUnused), you also need to compile sources beforehand, e.g.:
mvn compile test-compile scalafix:scalafix
You can tweak plugin execution using some parameters, e.g.:
mvn scalafix:scalafix -Dscalafix.mode=CHECK -Dscalafix.skipTest=true
Also, you can pass parameters via pom.xml:
<plugins>
<plugin>
<groupId>io.github.evis</groupId>
<artifactId>scalafix-maven-plugin</artifactId>
<version>0.1.4_0.9.23</version>
<configuration>
<mode>CHECK</mode>
<skipTest>true</skipTest>
</configuration>
</plugin>
</plugins>
If you want to use external rules, add jars containing rules to dependencies of the plugin:
<plugin>
<groupId>io.github.evis</groupId>
<artifactId>scalafix-maven-plugin</artifactId>
<version>0.1.4_0.9.23</version>
<dependencies>
<dependency>
<groupId>com.nequissimus</groupId>
<artifactId>sort-imports_2.12</artifactId>
<version>0.5.5</version>
</dependency>
</dependencies>
</plugin>
Plugin parameters
| CLI name | Maven configuration name | Type | Description |
|---|---|---|---|
scalafix.mode |
mode |
ScalafixMainMode: either IN_PLACE, CHECK, STDOUT or AUTO_SUPPRESS_LINTER_ERRORS (default: IN_PLACE) |
Describes mode in which Scalafix runs. Description of different parameter values can be found in Scalafix javadoc. |
scalafix.command.line.args |
commandLineArgs |
String (default: empty string) |
Custom CLI arguments to pass into Scalafix. Description of available arguments can be found in Scalafix CLI documentation. |
scalafix.skip |
skip |
Boolean (default: false) |
Whether we should skip all formatting. |
scalafix.skip.main |
skipMain |
Boolean (default: false) |
Whether we should skip formatting of application/library sources (by default located in main/scala). |
scalafix.skip.test |
skipTest |
Boolean (default: false) |
Whether we should skip formatting of test sources (by default located in /test/scala). |
scalafix.config |
config |
File (default: .scalafix.conf) |
Configuration with rules to invoke for Scalafix. |
Tips and tricks
scalafix.mode=AUTO_SUPPRESS_LINTER_ERRORSis useful on the first execution of Scalafix: it allows to effectively ignore warnings in existing large codebase.scalafix.mode=CHECKis convenient to use in continuous integration builds: e.g., to disallow merging code with identified problems.scalafix.skip=trueis especially useful for Maven modules which don't contain Scala sources at all.scalafix.command.lineis great for applying those Scalafix parameters which aren't directly supported by plugin yet.- SemanticDB compiler plugin may slow down compilation a little bit. If you want to use it only for Scalafix, you can make separate Maven profile, e.g.:
<profiles>
<profile>
<id>semanticdb</id>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>${scala-maven-plugin.version}</version>
<configuration>
<compilerPlugins>
<compilerPlugin>
<groupId>org.scalameta</groupId>
<artifactId>semanticdb-scalac_${scala.version}</artifactId>
<version>${semanticdb.version}</version>
</compilerPlugin>
</compilerPlugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
</profile>
</profiles>
Then, run Scalafix like this:
mvn clean compile test-compile scalafix:scalafix -Psemanticdb
So, when you run compilation with profile turned off, then SemanticDB compiler plugin doesn't affect compilation time at all.
- Sometimes it makes sense to make different requirements about main and test code quality. To achieve it you can make separate test config, and invoke plugin twice, e.g.:
mvn clean compile scalafix:scalafix # this invocation uses .scalafix.conf
mvn test-compile scalafix:scalafix -Dscalafix.config=.scalafix.test.conf # means that rules for test code are located in file .scalafix.test.conf
Contributing
Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. If you need some help with your PR at any time, please feel free to mention @evis.
Support
The best way to get help is to open an issue. You can do it for things like asking questions about the project or requesting technical help.