added skip parameter to be used when generated sources are up to date

src/main/java/org/quickfixj/codegenerator/GenerateMojo.java

@@ -93,6 +93,13 @@ public class GenerateMojo extends AbstractMojo {
     @Parameter(defaultValue = "true")
     private boolean overwrite = true;
 
+    /**
+     * Skips code generation, e.g. when the generated sources are known to be up to date.
+     * The output directory is still added as a compile source root.
+     */
+    @Parameter(property = "quickfixj.codegenerator.skip", defaultValue = "false")
+    private boolean skip;
+
     /**
      * The Maven project to act upon.
      */
@@ -111,6 +118,14 @@ public class GenerateMojo extends AbstractMojo {
      */
     public void execute() throws MojoExecutionException {
 
+        if (skip) {
+            log("Skipping code generation for " + dictFile);
+            if (project != null) {
+                project.addCompileSourceRoot(outputDirectory.getAbsolutePath());
+            }
+            return;
+        }
+
         if (!outputDirectory.exists()) {
             FileUtils.mkdir(outputDirectory.getAbsolutePath());
         }
@@ -338,4 +353,18 @@ public boolean isOverwrite() {
     public void setOverwrite(boolean overwrite) {
         this.overwrite = overwrite;
     }
+
+    /**
+     * @return whether code generation is skipped
+     */
+    public boolean isSkip() {
+        return skip;
+    }
+
+    /**
+     * @param skip sets whether code generation is skipped
+     */
+    public void setSkip(boolean skip) {
+        this.skip = skip;
+    }
 }

src/test/java/org/quickfixj/codegenerator/SkipTest.java

@@ -0,0 +1,46 @@
+package org.quickfixj.codegenerator;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.maven.plugin.MojoExecutionException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class SkipTest {
+
+    private File outputDirectory = new File("./target/test-output-skip/");
+    private File dictFile = new File("./src/test/resources/FIX41.xml");
+    private GenerateMojo mojo;
+
+    @BeforeEach
+    public void setup() throws IOException {
+        if (outputDirectory.exists()) {
+            FileUtils.deleteDirectory(outputDirectory);
+        }
+        mojo = new GenerateMojo();
+        mojo.setDictFile(dictFile);
+        mojo.setOutputDirectory(outputDirectory);
+        mojo.setSchemaDirectory(new File("./src/main/resources/org/quickfixj/codegenerator"));
+        mojo.setPackaging("quickfix.fix41");
+    }
+
+    @Test
+    public void testNothingGeneratedWhenSkipTrue() throws MojoExecutionException {
+        mojo.setSkip(true);
+        mojo.execute();
+
+        assertFalse(new File(outputDirectory, "quickfix/field/AllocShares.java").exists());
+    }
+
+    @Test
+    public void testGeneratedWhenSkipFalse() throws MojoExecutionException {
+        mojo.setSkip(false);
+        mojo.execute();
+
+        assertTrue(new File(outputDirectory, "quickfix/field/AllocShares.java").exists());
+    }
+}