Merge branch 'bug-1481'

pmd-core/src/main/java/net/sourceforge/pmd/cpd/CPDCommandLineInterface.java

@@ -86,8 +86,8 @@ public class CPDCommandLineInterface {
             }
 
             cpd.go();
-            if (cpd.getMatches().hasNext()) {
             System.out.println(arguments.getRenderer().render(cpd.getMatches()));
+            if (cpd.getMatches().hasNext()) {
                 if (arguments.isFailOnViolation()) {
                     setStatusCodeOrExit(DUPLICATE_CODE_FOUND);
                 } else {

pmd-core/src/test/java/net/sourceforge/pmd/cpd/CPDCommandLineInterfaceTest.java

@@ -0,0 +1,33 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.cpd;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.contrib.java.lang.system.LogMode;
+import org.junit.contrib.java.lang.system.RestoreSystemProperties;
+import org.junit.contrib.java.lang.system.StandardOutputStreamLog;
+import org.junit.rules.TestRule;
+
+public class CPDCommandLineInterfaceTest {
+    @Rule
+    public final TestRule restoreSystemProperties = new RestoreSystemProperties();
+    @Rule
+    public final StandardOutputStreamLog log = new StandardOutputStreamLog(LogMode.LOG_ONLY);
+
+    @Test
+    public void testEmptyResultRendering() {
+        System.setProperty(CPDCommandLineInterface.NO_EXIT_AFTER_RUN, "true");
+        CPDCommandLineInterface.main(new String[] {
+                "--minimum-tokens", "340",
+                "--language", "java",
+                "--files", "src/test/resources/net/sourceforge/pmd/cpd/files/",
+                "--format", "xml"
+        });
+        Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<pmd-cpd/>\n", log.getLog());
+    }
+
+}

pmd-javascript/src/test/java/net/sourceforge/pmd/cpd/CPDCommandLineInterfaceTest.java

@@ -23,6 +23,6 @@ public class CPDCommandLineInterfaceTest extends BaseCPDCLITest {
         runCPD("--minimum-tokens", "5", "--language", "js", "--files", "src/test/resources/net/sourceforge/pmd/cpd/ts/");
 
         String out = getOutput();
-        Assert.assertTrue(out.isEmpty());
+        Assert.assertTrue(out.trim().isEmpty());
     }
 }

src/site/markdown/overview/changelog.md

@@ -144,6 +144,7 @@ you'll need a java8 runtime environment.
     *   [#1470](https://sourceforge.net/p/pmd/bugs/1470/): Error with type-bound lambda
     *   [#1478](https://sourceforge.net/p/pmd/bugs/1478/): PMD CLI - Use first language as default if Java is not available
     *   [#1485](https://sourceforge.net/p/pmd/bugs/1485/): Analysis of some apex classes cause a stackoverflow error
+    *   [#1481](https://sourceforge.net/p/pmd/bugs/1481/): no problems found results in blank file instead of empty xml
 
 **API Changes:**
 
@@ -152,6 +153,7 @@ you'll need a java8 runtime environment.
 *   CPD: If a complete filename is specified, the language dependent filename filter is not applied. This allows
     to scan files, that are not using the standard file extension. If a directory is specified, the filename filter
     is still applied and only those files with the correct file extension of the language are scanned.
+*   CPD: If no problems found, an empty report will be output instead of nothing. See also [#1481](https://sourceforge.net/p/pmd/bugs/1481/)
 *   New command line parameter for PMD: `-norulesetcompatibility` - this disables the ruleset factory
     compatibility filter and fails, if e.g. an old rule name is used in the ruleset.
     See also [#1360](https://sourceforge.net/p/pmd/bugs/1360/).