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Semantic Versioning is a Java library allowing to validate if library version numbers follows Semantic Versioning principles as defined by [http://semver.org](Semantic Versioning).

Project version number changes implication are not always clearly identified. Will this patch released be safe to use in my project? 
Does this minor version increment implies my implementation of some API is no more complete? 
  
Semantic Versioning can check JAR files to identify breaking changes between versions and identify if your version number is correct according to Semantic Versioning principles.

# CLI

This simple command line tool looks at Java JAR files and determine API changes.

## Built-in help

```
% java -jar semver.jar --help
Semantic Version validator.

Usage: semver [options]

Options:
  --base-jar JAR          The base jar.
  --base-version VERSION  Version of the base jar (given with --base-jar).
  --check,-c              Check the compatibility of two jars.
  --diff,-d               Show the differences between two jars.
  --excludes EXCLUDE;...  Semicolon separated list of full qualified class names
                          to be excluded.
  --help,-h               Show this help and exit.
  --includes INCLUDE;...  Semicolon separated list of full qualified class names
                          to be included.
  --infer,-i              Infer the version of the new jar based on the previous
                          jar.
  --new-jar JAR           The new jar.
  --new-version VERSION   Version of the new jar (given with --new-jar).
  --validate,-v           Validate that the versions of two jars fulfil the
                          semver specification.
```

## Diff

Dump all changes between two JARs on standard output.

```
% java -jar semver.jar --diff --base-jar previousJar --new-jar current.jar
Class org.project.MyClass
 Added Class 
Class org.project.MyClass2
 Added Method method1
 Removed Field field1
 Changed Field field2 removed: final
```

## Check

Check compatibility type between two JARs.

```
% java -jar semver.jar --check --base-jar previousJar --new-jar current.jar
BACKWARD_COMPATIBLE_IMPLEMENTER
```

## Infer

Infer JAR version based on a previously versioned JAR.

```
% java -jar semver.jar --infer --base-version 1.0.0 --base-jar previous.jar --new-jar current.jar
1.0.1
```

## Validate

Validate JAR version based on a previously versioned JAR.

```
% java -jar semver.jar --validate --base-version 1.0.0 --base-jar previous.jar --new-version 1.0.1 --new-jar current.jar
true
```

# Enforcer Rule

The enforcer rule offers a rule for checking project's version against a previously released artifact.

## Checking a project's compatibility

In order to check your project's compatibility, you must add the enforcer rule as a dependency to
the maven-enforcer-plugin and then configure the maven-enforcer-plugin to run the rule:

```xml
<project>
  ...
  <build>
    ...
    <plugins>
      ...
      <plugin>
        <artifactId>maven-enforcer-plugin</artifactId>
        <version>1.0.1</version>
        ...
        <dependencies>
            ...
            <dependency>
                <groupId>org.semver</groupId>
                <artifactId>enforcer-rule</artifactId>
                <version>0.9.16</version>
            </dependency>
            ...
        </dependencies>
        ...
        <executions>
           ....
          <execution>
            <id>check</id>
            <phase>verify</phase>
            <goals>
              <goal>enforce</goal>
            </goals>
            <configuration>
              <rules>
                <requireBackwardCompatibility implementation="org.semver.enforcer.RequireBackwardCompatibility">
                  <compatibilityType>BACKWARD_COMPATIBLE_IMPLEMENTER</compatibilityType>
                </requireBackwardCompatibility>
              </rules>
            </configuration>
          </execution>
          ...
        </executions>
        ...
      </plugin>
      ...
    </plugins>
    ...
  </build>
  ...
</project>
```

Once you have configured your project, maven-enforcer will be able to throw a build error if current version is not backward compatible with last released one. 

You can force strict checking (i.e. compatibility type must exactly match specified one):

```xml
<configuration>
  <rules>
    <requireBackwardCompatibility implementation="org.semver.enforcer.RequireBackwardCompatibility">
      ...
      <strictChecking>true</strictChecking>
      ...
    </requireBackwardCompatibility>
  </rules>
</configuration>
```

## Checking a project's version

In order to check your project's version, you must add the enforcer rule as a dependency to
the maven-enforcer-plugin and then configure the maven-enforcer-plugin to run the rule:

```xml
<project>
  ...
  <build>
    ...
    <plugins>
      ...
      <plugin>
        <artifactId>maven-enforcer-plugin</artifactId>
        <version>1.0.1</version>
        ...
        <dependencies>
            ...
            <dependency>
                <groupId>org.semver</groupId>
                <artifactId>enforcer-rule</artifactId>
                <version>0.9.12</version>
            </dependency>
            ...
        </dependencies>
        ...
        <executions>
           ....
          <execution>
            <id>check</id>
            <phase>verify</phase>
            <goals>
              <goal>enforce</goal>
            </goals>
            <configuration>
              <rules>
                <requireSemanticVersioningConformance implementation="org.semver.enforcer.RequireSemanticVersioningConformance" />
              </rules>
            </configuration>
          </execution>
          ...
        </executions>
        ...
      </plugin>
      ...
    </plugins>
    ...
  </build>
  ...
</project>
```

Once you have configured your project, maven-enforcer will be able to throw a build error if current version follows semantic versioning principles. 

## Dumping details

Dump details of detected changes:

```xml
<configuration>
  <rules>
    <require...>
      ...
      <dumpDetails>true</dumpDetails>
      ...
    </require...>
  </rules>
</configuration>
```

## Checking against a well known version

You can force check with a well known version:

```xml
<configuration>
  <rules>
    <require...>
      ...
      <previousVersion>1.0.0</previousVersion>
      ...
    </require...>
  </rules>
</configuration>
```

## Filtering

Both rules allow to filter classes/packages:

```xml
<require...>
  ...
  <includes>
    <include>org.project.MyClass</include>
    <include>org.project.internal</include>
  </includes>
  <excludes>
    <exclude>org.project.MyClass</exclude>
    <exclude>org.project.internal</exclude>
  </excludes>
  ...
</require...>
```

# API overview

Semantic Versioning also provides an API for programmatically validating your project's version number.

```java
final File previousJar = ...;
final File currentJar = ...;
        
final Comparer comparer = new Comparer(previousJar, currentJar, ..., ...);
final Delta delta = comparer.diff();

final String compatibilityType = ...;

//Validates that computed and provided compatibility type are compatible.
final Delta.CompatibilityType expectedCompatibilityType = Delta.CompatibilityType.valueOf(compatibilityType);
final Delta.CompatibilityType detectedCompatibilityType = delta.computeCompatibilityType();
if (detectedCompatibilityType.compareTo(expectedCompatibilityType) > 0) {
  //Not compatible.
}

//Provide version number for previous and current Jar files.
final Version previous = Version.parse(...);
final Version current = Version.parse(...);

//Validates that current version number is valid based on semantic versioning principles.
final boolean compatible = delta.validate(previous, current);
```

# Maven dependency

```xml
<dependency>
    <groupId>org.semver</groupId>
    <artifactId>enforcer-rule</artifactId>
    <version>0.9.16</version>
</dependency>
```

Released under [Apache 2 license](http://www.apache.org/licenses/LICENSE-2.0.html).