Issue #251: auto generate patch file during maven build

Author: romani

.gitignore

@@ -6,6 +6,5 @@ net.sf.eclipsecs.core/lib/metadata-gen-1.0-SNAPSHOT.jar
 *.iml
 *.prefs
 .checkstyle
-net.sf.eclipsecs.core/lib/patch-filter-1.0-SNAPSHOT.jar
 target/
-patch-filters/
+show.patch

.travis.yml

@@ -27,19 +27,19 @@ matrix:
     - jdk: openjdk8
       env:
         - DESC="install (openjdk8)"
-        - CMD="./build-metafile-gen.sh && mkdir -p target && git diff HEAD~1 HEAD > target/show.patch && mvn install && git diff"
+        - CMD="./build-metafile-gen.sh && mvn install && git diff"
 
     # JDK 11 (Long Term Support version)
     - jdk: openjdk11
       env:
         - DESC="install (openjdk11)"
-        - CMD="./build-metafile-gen.sh && mkdir -p target && git diff HEAD~1 HEAD > target/show.patch && mvn install && git diff"
+        - CMD="./build-metafile-gen.sh && mvn install && git diff"
 
     # JDK 13 (most recent Java version)
     - jdk: openjdk13
       env:
         - DESC="install (openjdk13)"
-        - CMD="./build-metafile-gen.sh && mkdir -p target && git diff HEAD~1 HEAD > target/show.patch && mvn install && git diff"
+        - CMD="./build-metafile-gen.sh && mvn install && git diff"
 
 script:
   - |

config/checkstyle_checks.xml

@@ -190,14 +190,14 @@
     </module>
 
     <module name="com.puppycrawl.tools.checkstyle.filters.SuppressionPatchFilter">
-        <property name="file" value="target/show.patch"/>
+        <property name="file" value="show.patch"/>
         <property name="strategy" value="patchedline" />
         <property name="neverSuppressedChecks" value="FileLength, NewlineAtEndOfFile, RegexpOnFilename" />
     </module>
 
     <module name="TreeWalker">
         <module name="com.puppycrawl.tools.checkstyle.filters.SuppressionJavaPatchFilter">
-            <property name="file" value="target/show.patch"/>
+            <property name="file" value="show.patch"/>
             <property name="strategy" value="patchedline" />
         </module>
 

config/checkstyle_sevntu_checks.xml

@@ -13,13 +13,13 @@
   </module>
 
   <module name="com.puppycrawl.tools.checkstyle.filters.SuppressionPatchFilter">
-    <property name="file" value="target/show.patch"/>
+    <property name="file" value="show.patch"/>
     <property name="strategy" value="patchedline" />
   </module>
 
   <module name="TreeWalker">
     <module name="com.puppycrawl.tools.checkstyle.filters.SuppressionJavaPatchFilter">
-      <property name="file" value="target/show.patch"/>
+      <property name="file" value="show.patch"/>
       <property name="strategy" value="patchedline" />
     </module>
 

pom.xml

@@ -120,6 +120,28 @@
                     </environments>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>3.0.0</version>
+                <executions>
+                    <execution>
+                      <phase>verify</phase>
+                      <goals>
+                        <goal>exec</goal>
+                      </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <executable>git</executable>
+                    <arguments>
+                      <argument>diff</argument>
+                      <argument>HEAD~1</argument>
+                      <argument>HEAD</argument>
+                    </arguments>
+                    <outputFile>${maven.multiModuleProjectDirectory}/show.patch</outputFile>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-checkstyle-plugin</artifactId>