SONAR-16057 Filesystem tests fail with NPE

2 files changed, 32 insertions, 6 deletions

diff --git a/sonar-plugin-api-impl/src/main/java/org/sonar/api/batch/fs/internal/DefaultFileSystem.java b/sonar-plugin-api-impl/src/main/java/org/sonar/api/batch/fs/internal/DefaultFileSystem.java
index 5dac87e073f..eea57a82444 100644
--- a/sonar-plugin-api-impl/src/main/java/org/sonar/api/batch/fs/internal/DefaultFileSystem.java
+++ b/sonar-plugin-api-impl/src/main/java/org/sonar/api/batch/fs/internal/DefaultFileSystem.java
@@ -43,6 +43,8 @@ import org.sonar.api.batch.fs.internal.predicates.OptimizedFilePredicateAdapter;
 import org.sonar.api.scan.filesystem.PathResolver;
 import org.sonar.api.utils.PathUtils;
 
+import static java.util.Collections.emptySet;
+
 /**
  * @since 4.2
  */
@@ -193,7 +195,7 @@ public class DefaultFileSystem implements FileSystem {
     private final Map<String, InputFile> fileMap = new HashMap<>();
     private final Map<String, Set<InputFile>> filesByNameCache = new HashMap<>();
     private final Map<String, Set<InputFile>> filesByExtensionCache = new HashMap<>();
-    private SortedSet<String> languages = new TreeSet<>();
+    private final SortedSet<String> languages = new TreeSet<>();
 
     @Override
     public Iterable<InputFile> inputFiles() {
@@ -207,12 +209,12 @@ public class DefaultFileSystem implements FileSystem {
 
     @Override
     public Iterable<InputFile> getFilesByName(String filename) {
-      return filesByNameCache.get(filename);
+      return filesByNameCache.getOrDefault(filename, emptySet());
     }
 
     @Override
     public Iterable<InputFile> getFilesByExtension(String extension) {
-      return filesByExtensionCache.get(extension);
+      return filesByExtensionCache.getOrDefault(extension, emptySet());
     }
 
     @Override
diff --git a/sonar-plugin-api-impl/src/test/java/org/sonar/api/batch/fs/internal/fs/DefaultFileSystemTest.java b/sonar-plugin-api-impl/src/test/java/org/sonar/api/batch/fs/internal/fs/DefaultFileSystemTest.java
index 1665fb271b1..e516adec9b6 100644
--- a/sonar-plugin-api-impl/src/test/java/org/sonar/api/batch/fs/internal/fs/DefaultFileSystemTest.java
+++ b/sonar-plugin-api-impl/src/test/java/org/sonar/api/batch/fs/internal/fs/DefaultFileSystemTest.java
@@ -112,13 +112,37 @@ public class DefaultFileSystemTest {
   }
 
   @Test
-  public void input_file_returns_null_if_file_not_found() {
+  public void inputFiles_using_optimized_predicates() {
+    fs.add(new TestInputFileBuilder("foo", "src/Foo.php").setLanguage("php").build());
+    fs.add(new TestInputFileBuilder("foo", "src/Bar.java").setLanguage("java").build());
+    fs.add(new TestInputFileBuilder("foo", "src/Baz.java").setLanguage("java").build());
+
+    assertThat(fs.inputFiles(fs.predicates().hasFilename("Foo.php"))).hasSize(1);
+    assertThat(fs.inputFiles(fs.predicates().hasFilename("unknown"))).isEmpty();
+    assertThat(fs.inputFiles(fs.predicates().hasExtension("java"))).hasSize(2);
+    assertThat(fs.inputFiles(fs.predicates().hasExtension("unknown"))).isEmpty();
+  }
+
+  @Test
+  public void hasFiles_using_optimized_predicates() {
+    fs.add(new TestInputFileBuilder("foo", "src/Foo.php").setLanguage("php").build());
+    fs.add(new TestInputFileBuilder("foo", "src/Bar.java").setLanguage("java").build());
+    fs.add(new TestInputFileBuilder("foo", "src/Baz.java").setLanguage("java").build());
+
+    assertThat(fs.hasFiles(fs.predicates().hasFilename("Foo.php"))).isTrue();
+    assertThat(fs.hasFiles(fs.predicates().hasFilename("unknown"))).isFalse();
+    assertThat(fs.hasFiles(fs.predicates().hasExtension("java"))).isTrue();
+    assertThat(fs.hasFiles(fs.predicates().hasExtension("unknown"))).isFalse();
+  }
+
+  @Test
+  public void inputFile_returns_null_if_file_not_found() {
     assertThat(fs.inputFile(fs.predicates().hasRelativePath("src/Bar.java"))).isNull();
     assertThat(fs.inputFile(fs.predicates().hasLanguage("cobol"))).isNull();
   }
 
   @Test
-  public void input_file_fails_if_too_many_results() {
+  public void inputFile_fails_if_too_many_results() {
     fs.add(new TestInputFileBuilder("foo", "src/Bar.java").setLanguage("java").build());
     fs.add(new TestInputFileBuilder("foo", "src/Baz.java").setLanguage("java").build());
 
@@ -128,7 +152,7 @@ public class DefaultFileSystemTest {
   }
 
   @Test
-  public void input_file_supports_non_indexed_predicates() {
+  public void inputFile_supports_non_indexed_predicates() {
     fs.add(new TestInputFileBuilder("foo", "src/Bar.java").setLanguage("java").build());
 
     // it would fail if more than one java file