#1337: match .java extension case-insensitively in PmdValidator

src/main/java/com/qulice/pmd/PmdValidator.java

@@ -12,6 +12,7 @@
 import java.io.File;
 import java.util.Collection;
 import java.util.LinkedList;
+import java.util.Locale;
 
 /**
  * Validates source code with PMD.
@@ -79,7 +80,7 @@ public Collection<File> getNonExcludedFiles(final Collection<File> files) {
             if (this.env.exclude("pmd", name)) {
                 continue;
             }
-            if (!name.matches("^.*\\.java$")) {
+            if (!name.toLowerCase(Locale.ROOT).endsWith(".java")) {
                 continue;
             }
             sources.add(file);

src/test/java/com/qulice/pmd/PmdValidatorTest.java

@@ -7,6 +7,7 @@
 import com.qulice.spi.Environment;
 import com.qulice.spi.Violation;
 import java.io.File;
+import java.util.Collection;
 import java.util.Collections;
 import org.hamcrest.MatcherAssert;
 import org.hamcrest.Matchers;
@@ -33,4 +34,49 @@ void findsProblemsInJavaFiles() throws Exception {
             Matchers.not(Matchers.<Violation>empty())
         );
     }
+
+    @Test
+    void acceptsJavaFilesWithUppercaseExtension() throws Exception {
+        final String file = "src/main/java/Main.JAVA";
+        final Environment env = new Environment.Mock()
+            .withFile(file, "class Main { int x = 0; }");
+        final Collection<File> kept = new PmdValidator(env).getNonExcludedFiles(
+            Collections.singletonList(new File(env.basedir(), file))
+        );
+        MatcherAssert.assertThat(
+            "Java files with uppercase .JAVA extension should not be skipped",
+            kept,
+            Matchers.hasSize(1)
+        );
+    }
+
+    @Test
+    void acceptsJavaFilesWithMixedCaseExtension() throws Exception {
+        final String file = "src/main/java/Main.Java";
+        final Environment env = new Environment.Mock()
+            .withFile(file, "class Main { int x = 0; }");
+        final Collection<File> kept = new PmdValidator(env).getNonExcludedFiles(
+            Collections.singletonList(new File(env.basedir(), file))
+        );
+        MatcherAssert.assertThat(
+            "Java files with mixed-case .Java extension should not be skipped",
+            kept,
+            Matchers.hasSize(1)
+        );
+    }
+
+    @Test
+    void skipsFilesThatAreNotJava() throws Exception {
+        final String file = "src/main/java/notes.txt";
+        final Environment env = new Environment.Mock()
+            .withFile(file, "hello");
+        final Collection<File> kept = new PmdValidator(env).getNonExcludedFiles(
+            Collections.singletonList(new File(env.basedir(), file))
+        );
+        MatcherAssert.assertThat(
+            "Non-Java files should be skipped",
+            kept,
+            Matchers.empty()
+        );
+    }
 }