SONAR-926 remove ModuleLanguages from API. Replaced by FileSystem#languages()

plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/sensors/ProfileEventsSensor.java

@@ -19,12 +19,8 @@
  */
 package org.sonar.plugins.core.sensors;
 
-import org.sonar.api.batch.Event;
-import org.sonar.api.batch.ModuleLanguages;
-import org.sonar.api.batch.Sensor;
-import org.sonar.api.batch.SensorContext;
-import org.sonar.api.batch.TimeMachine;
-import org.sonar.api.batch.TimeMachineQuery;
+import org.sonar.api.batch.*;
+import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.measures.CoreMetrics;
 import org.sonar.api.measures.Measure;
 import org.sonar.api.measures.Metric;
@@ -38,12 +34,12 @@ public class ProfileEventsSensor implements Sensor {
 
   private final RulesProfile profile;
   private final TimeMachine timeMachine;
-  private final ModuleLanguages moduleLanguages;
+  private final FileSystem fs;
 
-  public ProfileEventsSensor(RulesProfile profile, TimeMachine timeMachine, ModuleLanguages moduleLanguages) {
+  public ProfileEventsSensor(RulesProfile profile, TimeMachine timeMachine, FileSystem fs) {
     this.profile = profile;
     this.timeMachine = timeMachine;
-    this.moduleLanguages = moduleLanguages;
+    this.fs = fs;
   }
 
   public boolean shouldExecuteOnProject(Project project) {
@@ -53,7 +49,7 @@ public class ProfileEventsSensor implements Sensor {
 
   public void analyse(Project project, SensorContext context) {
     RulesProfileWrapper profileWrapper = (RulesProfileWrapper) profile;
-    for (String languageKey : moduleLanguages.keys()) {
+    for (String languageKey : fs.languages()) {
       RulesProfile realProfile = profileWrapper.getProfileByLanguage(languageKey);
       Measure pastProfileMeasure = getPreviousMeasure(project, CoreMetrics.PROFILE);
       if (pastProfileMeasure == null) {

plugins/sonar-core-plugin/src/test/java/org/sonar/plugins/core/sensors/ProfileEventsSensorTest.java

@@ -25,15 +25,13 @@ import org.sonar.api.batch.Event;
 import org.sonar.api.batch.SensorContext;
 import org.sonar.api.batch.TimeMachine;
 import org.sonar.api.batch.TimeMachineQuery;
-import org.sonar.api.config.Settings;
+import org.sonar.api.batch.fs.FileSystem;
+import org.sonar.api.batch.fs.internal.DefaultFileSystem;
 import org.sonar.api.measures.CoreMetrics;
 import org.sonar.api.measures.Measure;
 import org.sonar.api.profiles.RulesProfile;
-import org.sonar.api.resources.Java;
-import org.sonar.api.resources.Languages;
 import org.sonar.api.resources.Project;
 import org.sonar.batch.rule.RulesProfileWrapper;
-import org.sonar.batch.scan.language.DefaultModuleLanguages;
 
 import java.util.Arrays;
 import java.util.Collections;
@@ -49,7 +47,7 @@ public class ProfileEventsSensorTest {
 
   Project project;
   SensorContext context;
-  DefaultModuleLanguages moduleLanguages;
+  FileSystem fs;
   RulesProfileWrapper wrapper;
   RulesProfile profile;
 
@@ -58,8 +56,7 @@ public class ProfileEventsSensorTest {
     project = mock(Project.class);
     context = mock(SensorContext.class);
 
-    moduleLanguages = new DefaultModuleLanguages(new Settings(), new Languages(Java.INSTANCE));
-    moduleLanguages.addLanguage("java");
+    fs = new DefaultFileSystem().addLanguages("java");
     profile = mock(RulesProfile.class);
     when(profile.getLanguage()).thenReturn("java");
     wrapper = new RulesProfileWrapper(profile);
@@ -68,7 +65,7 @@ public class ProfileEventsSensorTest {
   @Test
   public void shouldExecuteWhenProfileWithId() {
     when(profile.getId()).thenReturn(123);
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, null, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, null, fs);
 
     assertThat(sensor.shouldExecuteOnProject(project)).isTrue();
     verifyZeroInteractions(project);
@@ -78,7 +75,7 @@ public class ProfileEventsSensorTest {
   public void shouldNotExecuteIfProfileIsNotWrapper() {
     RulesProfile profile = mock(RulesProfile.class);
     when(profile.getId()).thenReturn(null);
-    ProfileEventsSensor sensor = new ProfileEventsSensor(profile, null, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(profile, null, fs);
 
     assertThat(sensor.shouldExecuteOnProject(project)).isFalse();
     verifyZeroInteractions(project);
@@ -88,7 +85,7 @@ public class ProfileEventsSensorTest {
   public void shouldDoNothingIfNoProfileChange() {
     mockProfileWithVersion(1);
     TimeMachine timeMachine = mockTM(22.0, "Foo", 1.0); // Same profile, same version
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, fs);
 
     sensor.analyse(project, context);
 
@@ -99,7 +96,7 @@ public class ProfileEventsSensorTest {
   public void shouldCreateEventIfProfileChange() {
     mockProfileWithVersion(1);
     TimeMachine timeMachine = mockTM(21.0, "Bar", 1.0); // Different profile
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, fs);
 
     sensor.analyse(project, context);
 
@@ -113,7 +110,7 @@ public class ProfileEventsSensorTest {
   public void shouldCreateEventIfProfileVersionChange() {
     mockProfileWithVersion(2);
     TimeMachine timeMachine = mockTM(22.0, "Foo", 1.0); // Same profile, different version
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, fs);
 
     sensor.analyse(project, context);
 
@@ -127,7 +124,7 @@ public class ProfileEventsSensorTest {
   public void shouldNotCreateEventIfFirstAnalysis() {
     mockProfileWithVersion(2);
     TimeMachine timeMachine = mockTM(null, null);
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, fs);
 
     sensor.analyse(project, context);
 
@@ -138,7 +135,7 @@ public class ProfileEventsSensorTest {
   public void shouldCreateEventIfFirstAnalysisWithVersionsAndVersionMoreThan1() {
     mockProfileWithVersion(2);
     TimeMachine timeMachine = mockTM(22.0, "Foo", null);
-    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, moduleLanguages);
+    ProfileEventsSensor sensor = new ProfileEventsSensor(wrapper, timeMachine, fs);
 
     sensor.analyse(project, context);
 

plugins/sonar-cpd-plugin/src/main/java/org/sonar/plugins/cpd/CpdSensor.java

@@ -23,9 +23,9 @@ import com.google.common.annotations.VisibleForTesting;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.sonar.api.CoreProperties;
-import org.sonar.api.batch.ModuleLanguages;
 import org.sonar.api.batch.Sensor;
 import org.sonar.api.batch.SensorContext;
+import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.config.Settings;
 import org.sonar.api.resources.Project;
 
@@ -36,13 +36,13 @@ public class CpdSensor implements Sensor {
   private CpdEngine sonarEngine;
   private CpdEngine sonarBridgeEngine;
   private Settings settings;
-  private ModuleLanguages moduleLanguages;
+  private FileSystem fs;
 
-  public CpdSensor(SonarEngine sonarEngine, SonarBridgeEngine sonarBridgeEngine, Settings settings, ModuleLanguages moduleLanguages) {
+  public CpdSensor(SonarEngine sonarEngine, SonarBridgeEngine sonarBridgeEngine, Settings settings, FileSystem fs) {
     this.sonarEngine = sonarEngine;
     this.sonarBridgeEngine = sonarBridgeEngine;
     this.settings = settings;
-    this.moduleLanguages = moduleLanguages;
+    this.fs = fs;
   }
 
   public boolean shouldExecuteOnProject(Project project) {
@@ -67,7 +67,7 @@ public class CpdSensor implements Sensor {
   }
 
   public void analyse(Project project, SensorContext context) {
-    for (String language : moduleLanguages.keys()) {
+    for (String language : fs.languages()) {
       if (isSkipped(language)) {
         LOG.info("Detection of duplicated code is skipped for {}", language);
         continue;

plugins/sonar-cpd-plugin/src/test/java/org/sonar/plugins/cpd/CpdSensorTest.java

@@ -21,13 +21,10 @@ package org.sonar.plugins.cpd;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.sonar.api.batch.fs.internal.DefaultFileSystem;
 import org.sonar.api.config.PropertyDefinitions;
 import org.sonar.api.config.Settings;
-import org.sonar.api.resources.AbstractLanguage;
 import org.sonar.api.resources.Java;
-import org.sonar.api.resources.Language;
-import org.sonar.api.resources.Languages;
-import org.sonar.batch.scan.language.DefaultModuleLanguages;
 import org.sonar.plugins.cpd.index.IndexFactory;
 
 import static org.fest.assertions.Assertions.assertThat;
@@ -46,7 +43,9 @@ public class CpdSensorTest {
     sonarEngine = new SonarEngine(indexFactory, null, null);
     sonarBridgeEngine = new SonarBridgeEngine(indexFactory, null, null);
     settings = new Settings(new PropertyDefinitions(CpdPlugin.class));
-    sensor = new CpdSensor(sonarEngine, sonarBridgeEngine, settings, new DefaultModuleLanguages(settings, new Languages()));
+
+    DefaultFileSystem fs = new DefaultFileSystem();
+    sensor = new CpdSensor(sonarEngine, sonarBridgeEngine, settings, fs);
   }
 
   @Test

sonar-batch/src/main/java/org/sonar/batch/phases/ProfileLogger.java

@@ -24,7 +24,7 @@ import org.apache.commons.lang.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.sonar.api.BatchComponent;
-import org.sonar.api.batch.ModuleLanguages;
+import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.config.Settings;
 import org.sonar.api.profiles.Alert;
 import org.sonar.api.profiles.RulesProfile;
@@ -39,15 +39,15 @@ public class ProfileLogger implements BatchComponent {
   private static final Logger LOG = LoggerFactory.getLogger(ProfileLogger.class);
 
   private final Settings settings;
-  private final ModuleLanguages languages;
+  private final FileSystem fs;
   private final ModuleQProfiles profiles;
   private final ProjectAlerts projectAlerts;
 
   private final RulesProfile rulesProfile;
 
-  public ProfileLogger(Settings settings, ModuleLanguages languages, ModuleQProfiles profiles, ProjectAlerts projectAlerts, RulesProfile rulesProfile) {
+  public ProfileLogger(Settings settings, FileSystem fs, ModuleQProfiles profiles, ProjectAlerts projectAlerts, RulesProfile rulesProfile) {
     this.settings = settings;
-    this.languages = languages;
+    this.fs = fs;
     this.profiles = profiles;
     this.projectAlerts = projectAlerts;
     this.rulesProfile = rulesProfile;
@@ -61,7 +61,7 @@ public class ProfileLogger implements BatchComponent {
   void execute(Logger logger) {
     String defaultName = settings.getString(ModuleQProfiles.SONAR_PROFILE_PROP);
     boolean defaultNameUsed = StringUtils.isBlank(defaultName);
-    for (String lang : languages.keys()) {
+    for (String lang : fs.languages()) {
       QProfile profile = profiles.findByLanguage(lang);
       if (profile == null) {
         logger.warn("No Quality profile found for language " + lang);
@@ -72,7 +72,7 @@ public class ProfileLogger implements BatchComponent {
         }
       }
     }
-    if (!defaultNameUsed && !languages.keys().isEmpty()) {
+    if (!defaultNameUsed && !fs.languages().isEmpty()) {
       throw MessageException.of("sonar.profile was set to '" + defaultName + "' but didn't match any profile for any language. Please check your configuration.");
     }
 
@@ -81,7 +81,7 @@ public class ProfileLogger implements BatchComponent {
 
   private void addModuleAlertsToProjectAlerts() {
     RulesProfileWrapper profileWrapper = (RulesProfileWrapper) rulesProfile;
-    for (String lang : languages.keys()) {
+    for (String lang : fs.languages()) {
       RulesProfile profile = profileWrapper.getProfileByLanguage(lang);
       for (Alert alert : profile.getAlerts()) {
         projectAlerts.add(alert);

sonar-batch/src/main/java/org/sonar/batch/rule/QProfileSensor.java

@@ -19,9 +19,10 @@
  */
 package org.sonar.batch.rule;
 
-import org.sonar.api.batch.ModuleLanguages;
+import com.google.common.collect.Iterables;
 import org.sonar.api.batch.Sensor;
 import org.sonar.api.batch.SensorContext;
+import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.measures.CoreMetrics;
 import org.sonar.api.measures.Measure;
 import org.sonar.api.resources.Project;
@@ -33,12 +34,12 @@ import org.sonar.core.qualityprofile.db.QualityProfileDao;
 public class QProfileSensor implements Sensor {
 
   private final ModuleQProfiles moduleQProfiles;
-  private final ModuleLanguages moduleLanguages;
+  private final FileSystem fs;
   private final QualityProfileDao dao;
 
-  public QProfileSensor(ModuleQProfiles moduleQProfiles, ModuleLanguages moduleLanguages, QualityProfileDao dao) {
+  public QProfileSensor(ModuleQProfiles moduleQProfiles, FileSystem fs, QualityProfileDao dao) {
     this.moduleQProfiles = moduleQProfiles;
-    this.moduleLanguages = moduleLanguages;
+    this.fs = fs;
     this.dao = dao;
   }
 
@@ -47,14 +48,14 @@ public class QProfileSensor implements Sensor {
   }
 
   public void analyse(Project project, SensorContext context) {
-    for (String language : moduleLanguages.keys()) {
+    for (String language : fs.languages()) {
       ModuleQProfiles.QProfile qProfile = moduleQProfiles.findByLanguage(language);
       if (qProfile != null) {
         dao.updateUsedColumn(qProfile.id(), true);
       }
     }
-    if (moduleLanguages.keys().size() == 1) {
-      String language = moduleLanguages.keys().iterator().next();
+    if (fs.languages().size() == 1) {
+      String language = Iterables.getOnlyElement(fs.languages());
       ModuleQProfiles.QProfile qProfile = moduleQProfiles.findByLanguage(language);
       if (qProfile != null) {
         Measure measure = new Measure(CoreMetrics.PROFILE, qProfile.name()).setValue((double)qProfile.id());

sonar-batch/src/main/java/org/sonar/batch/scan/language/DefaultModuleLanguages.java → sonar-batch/src/main/java/org/sonar/batch/scan/LanguageVerifier.java

@@ -17,50 +17,47 @@
  * along with this program; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-package org.sonar.batch.scan.language;
+package org.sonar.batch.scan;
 
-import com.google.common.collect.Sets;
+import org.picocontainer.Startable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.sonar.api.CoreProperties;
-import org.sonar.api.batch.ModuleLanguages;
 import org.sonar.api.config.Settings;
 import org.sonar.api.resources.Language;
 import org.sonar.api.resources.Languages;
 import org.sonar.api.utils.MessageException;
 
-import java.util.Collection;
-import java.util.Set;
-
 /**
- * Give access to all languages detected on the current module
- *
- * @since 4.2
+ * Verifies that the property sonar.language is valid
  */
-public class DefaultModuleLanguages implements ModuleLanguages {
+public class LanguageVerifier implements Startable {
+
+  private static final Logger LOG = LoggerFactory.getLogger(LanguageVerifier.class);
+
+  private final Settings settings;
+  private final Languages languages;
 
-  private static final Logger LOG = LoggerFactory.getLogger(DefaultModuleLanguages.class);
+  public LanguageVerifier(Settings settings, Languages languages) {
+    this.settings = settings;
+    this.languages = languages;
+  }
 
-  private final Set<String> moduleLanguages = Sets.newTreeSet();
 
-  public DefaultModuleLanguages(Settings settings, Languages languages) {
+  @Override
+  public void start() {
     if (settings.hasKey(CoreProperties.PROJECT_LANGUAGE_PROPERTY)) {
       String languageKey = settings.getString(CoreProperties.PROJECT_LANGUAGE_PROPERTY);
       LOG.info("Language is forced to {}", languageKey);
       Language language = languages.get(languageKey);
       if (language == null) {
-        throw MessageException.of("You must install a plugin that supports the language key '" + languageKey + "'");
+        throw MessageException.of("You must install a plugin that supports the language '" + languageKey + "'");
       }
-      addLanguage(languageKey);
     }
   }
 
-  public void addLanguage(String languageKey) {
-    moduleLanguages.add(languageKey);
-  }
-
   @Override
-  public Collection<String> keys() {
-    return moduleLanguages;
+  public void stop() {
+    // nothing to do
   }
 }

sonar-batch/src/main/java/org/sonar/batch/scan/ModuleScanContainer.java

@@ -61,7 +61,6 @@ import org.sonar.batch.rule.QProfileSensor;
 import org.sonar.batch.rule.RulesProfileProvider;
 import org.sonar.batch.scan.filesystem.*;
 import org.sonar.batch.scan.filesystem.FileIndexer;
-import org.sonar.batch.scan.language.DefaultModuleLanguages;
 import org.sonar.batch.scan.report.JsonReport;
 import org.sonar.core.component.ScanPerspectives;
 import org.sonar.core.measure.MeasurementFilters;
@@ -112,7 +111,7 @@ public class ModuleScanContainer extends ComponentContainer {
       PreviousFileHashLoader.class,
       FileIndexer.class,
       ComponentIndexer.class,
-      DefaultModuleLanguages.class,
+      LanguageVerifier.class,
       FileSystemLogger.class,
       DefaultProjectClasspath.class,
       DefaultModuleFileSystem.class,

sonar-batch/src/main/java/org/sonar/batch/scan/filesystem/ComponentIndexer.java

@@ -30,10 +30,12 @@ import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.batch.fs.InputFile;
 import org.sonar.api.batch.fs.internal.DefaultInputFile;
 import org.sonar.api.config.Settings;
-import org.sonar.api.resources.*;
+import org.sonar.api.resources.File;
+import org.sonar.api.resources.Languages;
+import org.sonar.api.resources.Project;
+import org.sonar.api.resources.Resource;
 import org.sonar.api.utils.SonarException;
 import org.sonar.batch.index.ResourceKeyMigration;
-import org.sonar.batch.scan.language.DefaultModuleLanguages;
 
 /**
  * Index all files/directories of the module in SQ database and importing source code.
@@ -46,17 +48,15 @@ public class ComponentIndexer implements BatchComponent {
   private final SonarIndex sonarIndex;
   private final ResourceKeyMigration migration;
   private final Project module;
-  private final DefaultModuleLanguages moduleLanguages;
   private InputFileCache fileCache;
 
   public ComponentIndexer(Project module, Languages languages, SonarIndex sonarIndex, Settings settings, ResourceKeyMigration migration,
-    DefaultModuleLanguages moduleLanguages, InputFileCache fileCache) {
+                          InputFileCache fileCache) {
     this.module = module;
     this.languages = languages;
     this.sonarIndex = sonarIndex;
     this.settings = settings;
     this.migration = migration;
-    this.moduleLanguages = moduleLanguages;
     this.fileCache = fileCache;
   }
 
@@ -73,8 +73,7 @@ public class ComponentIndexer implements BatchComponent {
       }
       Resource sonarFile = File.create(inputFile.relativePath(), pathFromSourceDir, languages.get(languageKey), unitTest);
       if (sonarFile != null) {
-        sonarFile.setDeprecatedKey(((DefaultInputFile)inputFile).deprecatedKey());
-        moduleLanguages.addLanguage(languageKey);
+        sonarFile.setDeprecatedKey(((DefaultInputFile) inputFile).deprecatedKey());
         sonarIndex.index(sonarFile);
         importSources(fs, shouldImportSource, inputFile, sonarFile);
       }

sonar-batch/src/test/java/org/sonar/batch/phases/ProfileLoggerTest.java

@@ -19,13 +19,12 @@
  */
 package org.sonar.batch.phases;
 
-import com.google.common.collect.Lists;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.slf4j.Logger;
-import org.sonar.api.batch.ModuleLanguages;
+import org.sonar.api.batch.fs.internal.DefaultFileSystem;
 import org.sonar.api.config.Settings;
 import org.sonar.api.profiles.Alert;
 import org.sonar.api.profiles.RulesProfile;
@@ -39,28 +38,23 @@ import java.util.Arrays;
 import java.util.Collections;
 
 import static org.fest.assertions.Assertions.assertThat;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.*;
 
 public class ProfileLoggerTest {
 
   @Rule
   public ExpectedException thrown = ExpectedException.none();
 
-  private ModuleLanguages languages;
-  private ModuleQProfiles profiles;
-  private Settings settings = new Settings();
-  private ProjectAlerts projectAlerts = new ProjectAlerts();
-  private RulesProfileWrapper rulesProfile = mock(RulesProfileWrapper.class);
-  private RulesProfile javaRulesProfile;
-  private RulesProfile cobolRulesProfile;
+  DefaultFileSystem fs = new DefaultFileSystem();
+  ModuleQProfiles profiles;
+  Settings settings = new Settings();
+  ProjectAlerts projectAlerts = new ProjectAlerts();
+  RulesProfileWrapper rulesProfile = mock(RulesProfileWrapper.class);
+  RulesProfile javaRulesProfile;
+  RulesProfile cobolRulesProfile;
 
   @Before
   public void before() {
-    languages = mock(ModuleLanguages.class);
-    when(languages.keys()).thenReturn(Lists.newArrayList("java", "cobol"));
-
     profiles = mock(ModuleQProfiles.class);
     QProfile javaProfile = mock(QProfile.class);
     when(javaProfile.name()).thenReturn("My Java profile");
@@ -76,7 +70,8 @@ public class ProfileLoggerTest {
 
   @Test
   public void should_log_all_used_profiles() {
-    ProfileLogger profileLogger = new ProfileLogger(settings, languages, profiles, projectAlerts, rulesProfile);
+    fs.addLanguages("java", "cobol");
+    ProfileLogger profileLogger = new ProfileLogger(settings, fs, profiles, projectAlerts, rulesProfile);
     Logger logger = mock(Logger.class);
     profileLogger.execute(logger);
 
@@ -86,9 +81,10 @@ public class ProfileLoggerTest {
 
   @Test
   public void should_fail_if_default_profile_not_used() {
+    fs.addLanguages("java", "cobol");
     settings.setProperty("sonar.profile", "Unknown");
 
-    ProfileLogger profileLogger = new ProfileLogger(settings, languages, profiles, projectAlerts, rulesProfile);
+    ProfileLogger profileLogger = new ProfileLogger(settings, fs, profiles, projectAlerts, rulesProfile);
 
     thrown.expect(MessageException.class);
     thrown.expectMessage("sonar.profile was set to 'Unknown' but didn't match any profile for any language. Please check your configuration.");
@@ -99,9 +95,8 @@ public class ProfileLoggerTest {
   @Test
   public void should_not_fail_if_no_language_on_project() {
     settings.setProperty("sonar.profile", "Unknown");
-    when(languages.keys()).thenReturn(Collections.<String>emptyList());
 
-    ProfileLogger profileLogger = new ProfileLogger(settings, languages, profiles, projectAlerts, rulesProfile);
+    ProfileLogger profileLogger = new ProfileLogger(settings, fs, profiles, projectAlerts, rulesProfile);
 
     profileLogger.execute();
 
@@ -109,15 +104,17 @@ public class ProfileLoggerTest {
 
   @Test
   public void should_not_fail_if_default_profile_used_at_least_once() {
+    fs.addLanguages("java", "cobol");
     settings.setProperty("sonar.profile", "My Java profile");
 
-    ProfileLogger profileLogger = new ProfileLogger(settings, languages, profiles, projectAlerts, rulesProfile);
+    ProfileLogger profileLogger = new ProfileLogger(settings, fs, profiles, projectAlerts, rulesProfile);
 
     profileLogger.execute();
   }
 
   @Test
   public void should_collect_alerts() {
+    fs.addLanguages("java", "cobol");
     Alert javaAlert1 = new Alert();
     Alert javaAlert2 = new Alert();
     Alert cobolAlert1 = new Alert();
@@ -125,10 +122,10 @@ public class ProfileLoggerTest {
     when(javaRulesProfile.getAlerts()).thenReturn(Arrays.asList(javaAlert1, javaAlert2));
     when(cobolRulesProfile.getAlerts()).thenReturn(Arrays.asList(cobolAlert1, cobolAlert2));
 
-    ProfileLogger profileLogger = new ProfileLogger(settings, languages, profiles, projectAlerts, rulesProfile);
+    ProfileLogger profileLogger = new ProfileLogger(settings, fs, profiles, projectAlerts, rulesProfile);
 
     profileLogger.execute();
 
-    assertThat(projectAlerts.all()).containsExactly(javaAlert1, javaAlert2, cobolAlert1, cobolAlert2);
+    assertThat(projectAlerts.all()).containsExactly(cobolAlert1, cobolAlert2, javaAlert1, javaAlert2);
   }
 }

sonar-batch/src/test/java/org/sonar/batch/rule/QProfileSensorTest.java

@@ -19,17 +19,16 @@
  */
 package org.sonar.batch.rule;
 
-import java.util.Collections;
 import org.junit.Test;
-import org.sonar.api.batch.ModuleLanguages;
 import org.sonar.api.batch.SensorContext;
+import org.sonar.api.batch.fs.internal.DefaultFileSystem;
 import org.sonar.api.measures.CoreMetrics;
 import org.sonar.api.resources.Project;
 import org.sonar.api.test.IsMeasure;
 import org.sonar.core.persistence.AbstractDaoTestCase;
 import org.sonar.core.qualityprofile.db.QualityProfileDao;
 
-import java.util.Arrays;
+import java.util.Collections;
 
 import static org.fest.assertions.Assertions.assertThat;
 import static org.mockito.Mockito.*;
@@ -37,14 +36,14 @@ import static org.mockito.Mockito.*;
 public class QProfileSensorTest extends AbstractDaoTestCase {
 
   ModuleQProfiles moduleQProfiles = mock(ModuleQProfiles.class);
-  ModuleLanguages moduleLanguages = mock(ModuleLanguages.class);
   Project project = mock(Project.class);
   SensorContext sensorContext = mock(SensorContext.class);
+  DefaultFileSystem fs = new DefaultFileSystem();
 
   @Test
   public void to_string() throws Exception {
     QualityProfileDao dao = mock(QualityProfileDao.class);
-    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, moduleLanguages, dao);
+    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, fs, dao);
     assertThat(sensor.toString()).isEqualTo("QProfileSensor");
   }
 
@@ -54,7 +53,7 @@ public class QProfileSensorTest extends AbstractDaoTestCase {
     QualityProfileDao dao = new QualityProfileDao(getMyBatis());
     when(moduleQProfiles.findAll()).thenReturn(Collections.<ModuleQProfiles.QProfile>emptyList());
 
-    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, moduleLanguages, dao);
+    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, fs, dao);
     assertThat(sensor.shouldExecuteOnProject(project)).isTrue();
     sensor.analyse(project, sensorContext);
 
@@ -70,9 +69,9 @@ public class QProfileSensorTest extends AbstractDaoTestCase {
     when(moduleQProfiles.findByLanguage("java")).thenReturn(new ModuleQProfiles.QProfile(dao.selectById(2)));
     when(moduleQProfiles.findByLanguage("php")).thenReturn(new ModuleQProfiles.QProfile(dao.selectById(3)));
     when(moduleQProfiles.findByLanguage("abap")).thenReturn(null);
-    when(moduleLanguages.keys()).thenReturn(Arrays.asList("java", "php", "abap"));
+    fs.addLanguages("java", "php", "abap");
 
-    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, moduleLanguages, dao);
+    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, fs, dao);
     assertThat(sensor.shouldExecuteOnProject(project)).isTrue();
     sensor.analyse(project, sensorContext);
 
@@ -90,9 +89,9 @@ public class QProfileSensorTest extends AbstractDaoTestCase {
     when(moduleQProfiles.findByLanguage("java")).thenReturn(new ModuleQProfiles.QProfile(dao.selectById(2)));
     when(moduleQProfiles.findByLanguage("php")).thenReturn(new ModuleQProfiles.QProfile(dao.selectById(3)));
     when(moduleQProfiles.findByLanguage("abap")).thenReturn(null);
-    when(moduleLanguages.keys()).thenReturn(Arrays.asList("java"));
+    fs.addLanguages("java");
 
-    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, moduleLanguages, dao);
+    QProfileSensor sensor = new QProfileSensor(moduleQProfiles, fs, dao);
     assertThat(sensor.shouldExecuteOnProject(project)).isTrue();
     sensor.analyse(project, sensorContext);
 

sonar-batch/src/test/java/org/sonar/batch/scan/LanguageVerifierTest.java

@@ -0,0 +1,69 @@
+/*
+ * SonarQube, open source software quality management tool.
+ * Copyright (C) 2008-2013 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * SonarQube is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * SonarQube is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.batch.scan;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.sonar.api.config.Settings;
+import org.sonar.api.resources.Java;
+import org.sonar.api.resources.Languages;
+import org.sonar.api.utils.MessageException;
+
+public class LanguageVerifierTest {
+
+  Settings settings = new Settings();
+  Languages languages = new Languages(Java.INSTANCE);
+
+  @Rule
+  public ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void language_is_not_set() throws Exception {
+    LanguageVerifier verifier = new LanguageVerifier(settings, languages);
+    verifier.start();
+
+    // no failure
+
+    verifier.stop();
+  }
+
+  @Test
+  public void language_is_valid() throws Exception {
+    settings.setProperty("sonar.language", "java");
+
+    LanguageVerifier verifier = new LanguageVerifier(settings, languages);
+    verifier.start();
+
+    // no failure
+
+    verifier.stop();
+  }
+
+  @Test
+  public void language_is_not_valid() throws Exception {
+    thrown.expect(MessageException.class);
+    thrown.expectMessage("You must install a plugin that supports the language 'php'");
+
+    settings.setProperty("sonar.language", "php");
+    LanguageVerifier verifier = new LanguageVerifier(settings, languages);
+    verifier.start();
+  }
+}

sonar-batch/src/test/java/org/sonar/batch/scan/filesystem/ComponentIndexerTest.java

@@ -36,7 +36,7 @@ import org.sonar.api.batch.fs.internal.DefaultInputFile;
 import org.sonar.api.config.Settings;
 import org.sonar.api.resources.*;
 import org.sonar.batch.index.ResourceKeyMigration;
-import org.sonar.batch.scan.language.DefaultModuleLanguages;
+import org.sonar.batch.scan.LanguageVerifier;
 
 import java.io.File;
 import java.io.IOException;
@@ -84,8 +84,7 @@ public class ComponentIndexerTest {
     fs.add(newInputFile("src/main/java2/foo/bar/Foo.java", "", "foo/bar/Foo.java", "java", false));
     fs.add(newInputFile("src/test/java/foo/bar/FooTest.java", "", "foo/bar/FooTest.java", "java", true));
     Languages languages = new Languages(Java.INSTANCE);
-    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), new DefaultModuleLanguages(settings, languages),
-      mock(InputFileCache.class));
+    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), mock(InputFileCache.class));
     indexer.execute(fs);
 
     verify(sonarIndex).index(org.sonar.api.resources.File.create("src/main/java/foo/bar/Foo.java", "foo/bar/Foo.java", Java.INSTANCE, false));
@@ -108,7 +107,7 @@ public class ComponentIndexerTest {
     fs.add(newInputFile("src/test/foo/bar/FooTest.cbl", "", "foo/bar/FooTest.cbl", "cobol", true));
 
     Languages languages = new Languages(cobolLanguage);
-    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), new DefaultModuleLanguages(settings, languages),
+    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class),
       mock(InputFileCache.class));
     indexer.execute(fs);
 
@@ -123,7 +122,7 @@ public class ComponentIndexerTest {
 
     fs.add(newInputFile("src/main/java/foo/bar/Foo.java", "sample code", "foo/bar/Foo.java", "java", false));
     Languages languages = new Languages(Java.INSTANCE);
-    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), new DefaultModuleLanguages(settings, languages),
+    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class),
       mock(InputFileCache.class));
     indexer.execute(fs);
 
@@ -163,7 +162,7 @@ public class ComponentIndexerTest {
       .setPathRelativeToSourceDir("foo/bar/Foo.java")
       .setLanguage("java"));
     Languages languages = new Languages(Java.INSTANCE);
-    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), new DefaultModuleLanguages(settings, languages),
+    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class),
       mock(InputFileCache.class));
     indexer.execute(fs);
 
@@ -189,7 +188,7 @@ public class ComponentIndexerTest {
       .setPathRelativeToSourceDir("foo/bar/Foo.java")
       .setLanguage("java"));
     Languages languages = new Languages(Java.INSTANCE);
-    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class), new DefaultModuleLanguages(settings, languages),
+    ComponentIndexer indexer = new ComponentIndexer(project, languages, sonarIndex, settings, mock(ResourceKeyMigration.class),
       mock(InputFileCache.class));
     indexer.execute(fs);
 

sonar-plugin-api/src/main/java/org/sonar/api/batch/ModuleLanguages.java

@@ -1,36 +0,0 @@
-/*
- * SonarQube, open source software quality management tool.
- * Copyright (C) 2008-2013 SonarSource
- * mailto:contact AT sonarsource DOT com
- *
- * SonarQube is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 3 of the License, or (at your option) any later version.
- *
- * SonarQube is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
- */
-package org.sonar.api.batch;
-
-import org.sonar.api.BatchComponent;
-import org.sonar.api.resources.Language;
-
-import java.util.Collection;
-
-/**
- * Give access to all languages detected on the current module.
- *
- * @since 4.2
- */
-public interface ModuleLanguages extends BatchComponent {
-
-  Collection<String> keys();
-
-}

sonar-plugin-api/src/main/java/org/sonar/api/batch/fs/FileSystem.java

@@ -24,7 +24,7 @@ import org.sonar.api.BatchComponent;
 import javax.annotation.CheckForNull;
 import java.io.File;
 import java.nio.charset.Charset;
-import java.util.Set;
+import java.util.SortedSet;
 
 /**
  * <p>The unit tests needing an instance of FileSystem can use the implementation
@@ -94,5 +94,5 @@ public interface FileSystem extends BatchComponent {
   /**
    * Languages detected in all files, whatever their type (main or test)
    */
-  Set<String> languages();
+  SortedSet<String> languages();
 }

sonar-plugin-api/src/main/java/org/sonar/api/batch/fs/internal/DefaultFileSystem.java

@@ -26,7 +26,6 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
-import org.apache.commons.io.Charsets;
 import org.sonar.api.batch.fs.FilePredicate;
 import org.sonar.api.batch.fs.FileSystem;
 import org.sonar.api.batch.fs.InputFile;
@@ -36,7 +35,10 @@ import javax.annotation.CheckForNull;
 import javax.annotation.Nullable;
 import java.io.File;
 import java.nio.charset.Charset;
-import java.util.*;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.SortedSet;
 
 /**
  * @since 4.2
@@ -44,10 +46,9 @@ import java.util.*;
 public class DefaultFileSystem implements FileSystem {
 
   private final Cache cache;
-  private final Set<String> languages = Sets.newTreeSet();
+  private final SortedSet<String> languages = Sets.newTreeSet();
   private File baseDir, workDir;
-  private Charset encoding = Charsets.UTF_8;
-  private boolean isDefaultJvmEncoding = false;
+  private Charset encoding;
 
   /**
    * Only for testing
@@ -71,22 +72,18 @@ public class DefaultFileSystem implements FileSystem {
     return baseDir;
   }
 
-  public DefaultFileSystem setEncoding(Charset e) {
+  public DefaultFileSystem setEncoding(@Nullable Charset e) {
     this.encoding = e;
     return this;
   }
 
   @Override
   public Charset encoding() {
-    return encoding;
+    return encoding == null ? Charset.defaultCharset() : encoding;
   }
 
   public boolean isDefaultJvmEncoding() {
-    return isDefaultJvmEncoding;
-  }
-
-  public void setIsDefaultJvmEncoding(boolean b) {
-    this.isDefaultJvmEncoding = b;
+    return encoding == null;
   }
 
   public DefaultFileSystem setWorkDir(File d) {
@@ -137,15 +134,31 @@ public class DefaultFileSystem implements FileSystem {
     });
   }
 
-  public void add(InputFile inputFile) {
+  /**
+   * Adds InputFile to the list and registers its language, if present.
+   */
+  public DefaultFileSystem add(InputFile inputFile) {
     cache.add(inputFile);
     if (inputFile.language() != null) {
       languages.add(inputFile.language());
     }
+    return this;
+  }
+
+  /**
+   * Adds a language to the list. To be used only for unit tests that need to use {@link #languages()} without
+   * using {@link #add(org.sonar.api.batch.fs.InputFile)}.
+   */
+  public DefaultFileSystem addLanguages(String language, String... others) {
+    languages.add(language);
+    for (String other : others) {
+      languages.add(other);
+    }
+    return this;
   }
 
   @Override
-  public Set<String> languages() {
+  public SortedSet<String> languages() {
     doPreloadFiles();
     return languages;
   }

sonar-plugin-api/src/main/java/org/sonar/api/batch/fs/internal/DefaultInputFile.java

@@ -20,7 +20,6 @@
 package org.sonar.api.batch.fs.internal;
 
 import org.apache.commons.io.FilenameUtils;
-import org.apache.commons.lang.StringUtils;
 import org.sonar.api.batch.fs.InputFile;
 import org.sonar.api.utils.PathUtils;
 
@@ -66,6 +65,9 @@ public class DefaultInputFile implements InputFile, org.sonar.api.resources.Inpu
 
   @Override
   public File file() {
+    if (absolutePath == null) {
+      throw new IllegalStateException("Can not return the java.io.File because absolute path is not set (see method setFile(java.io.File))");
+    }
     return new File(absolutePath);
   }
 

sonar-plugin-api/src/main/java/org/sonar/api/resources/Project.java

@@ -26,7 +26,6 @@ import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang.builder.ToStringBuilder;
 import org.apache.maven.project.MavenProject;
 import org.sonar.api.CoreProperties;
-import org.sonar.api.batch.ModuleLanguages;
 import org.sonar.api.component.Component;
 
 import java.util.ArrayList;
@@ -241,7 +240,7 @@ public class Project extends Resource implements Component {
 
   /**
    * @return the project language when there is only one language
-   * @deprecated since 4.2 use {@link ModuleLanguages}
+   * @deprecated since 4.2 use {@link org.sonar.api.batch.fs.FileSystem#languages()}
    */
   @Deprecated
   @Override
@@ -259,7 +258,7 @@ public class Project extends Resource implements Component {
 
   /**
    * @return the language key or empty if no language is specified
-   * @deprecated since 4.2 use {@link ModuleLanguages}
+   * @deprecated since 4.2 use {@link org.sonar.api.batch.fs.FileSystem#languages()}
    */
   @Deprecated
   public String getLanguageKey() {

sonar-plugin-api/src/test/java/org/sonar/api/batch/fs/internal/DefaultFileSystemTest.java

@@ -0,0 +1,137 @@
+/*
+ * SonarQube, open source software quality management tool.
+ * Copyright (C) 2008-2013 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * SonarQube is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * SonarQube is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.api.batch.fs.internal;
+
+import com.google.common.base.Charsets;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.rules.TemporaryFolder;
+import org.sonar.api.batch.fs.FilePredicates;
+
+import java.io.File;
+import java.nio.charset.Charset;
+
+import static org.fest.assertions.Assertions.assertThat;
+
+public class DefaultFileSystemTest {
+
+  @Rule
+  public TemporaryFolder temp = new TemporaryFolder();
+
+  @Rule
+  public ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void test_directories() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+
+    File basedir = temp.newFolder();
+    fs.setBaseDir(basedir);
+    assertThat(fs.baseDir()).isAbsolute().isDirectory().exists();
+    assertThat(fs.baseDir().getCanonicalPath()).isEqualTo(basedir.getCanonicalPath());
+
+    File workdir = temp.newFolder();
+    fs.setWorkDir(workdir);
+    assertThat(fs.workDir()).isAbsolute().isDirectory().exists();
+    assertThat(fs.workDir().getCanonicalPath()).isEqualTo(workdir.getCanonicalPath());
+  }
+
+  @Test
+  public void test_encoding() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+
+    assertThat(fs.isDefaultJvmEncoding()).isTrue();
+    assertThat(fs.encoding()).isEqualTo(Charset.defaultCharset());
+
+    fs.setEncoding(Charsets.ISO_8859_1);
+    assertThat(fs.encoding()).isEqualTo(Charsets.ISO_8859_1);
+    assertThat(fs.isDefaultJvmEncoding()).isFalse();
+  }
+
+  @Test
+  public void add_languages() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+
+    assertThat(fs.languages()).isEmpty();
+
+    fs.addLanguages("java", "php", "cobol");
+    assertThat(fs.languages()).containsOnly("cobol", "java", "php");
+  }
+
+  @Test
+  public void files() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+
+    assertThat(fs.inputFiles(FilePredicates.all())).isEmpty();
+
+    fs.add(new DefaultInputFile("src/Foo.php").setLanguage("php").setFile(temp.newFile()));
+    fs.add(new DefaultInputFile("src/Bar.java").setLanguage("java").setFile(temp.newFile()));
+    fs.add(new DefaultInputFile("src/Baz.java").setLanguage("java").setFile(temp.newFile()));
+
+    // no language
+    fs.add(new DefaultInputFile("src/readme.txt").setFile(temp.newFile()));
+
+    assertThat(fs.inputFile(FilePredicates.hasRelativePath("src/Bar.java"))).isNotNull();
+    assertThat(fs.inputFile(FilePredicates.hasRelativePath("does/not/exist"))).isNull();
+
+    assertThat(fs.files(FilePredicates.all())).hasSize(4);
+    assertThat(fs.files(FilePredicates.hasLanguage("java"))).hasSize(2);
+    assertThat(fs.files(FilePredicates.hasLanguage("cobol"))).isEmpty();
+
+    assertThat(fs.hasFiles(FilePredicates.all())).isTrue();
+    assertThat(fs.hasFiles(FilePredicates.hasLanguage("java"))).isTrue();
+    assertThat(fs.hasFiles(FilePredicates.hasLanguage("cobol"))).isFalse();
+
+    assertThat(fs.inputFiles(FilePredicates.all())).hasSize(4);
+    assertThat(fs.inputFiles(FilePredicates.hasLanguage("php"))).hasSize(1);
+    assertThat(fs.inputFiles(FilePredicates.hasLanguage("java"))).hasSize(2);
+    assertThat(fs.inputFiles(FilePredicates.hasLanguage("cobol"))).isEmpty();
+
+    assertThat(fs.languages()).containsOnly("java", "php");
+  }
+
+  @Test
+  public void input_file_returns_null_if_file_not_found() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+    assertThat(fs.inputFile(FilePredicates.hasRelativePath("src/Bar.java"))).isNull();
+  }
+
+  @Test
+  public void input_file_fails_if_too_many_results() throws Exception {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("expected one element");
+
+    DefaultFileSystem fs = new DefaultFileSystem();
+    fs.add(new DefaultInputFile("src/Bar.java").setLanguage("java").setFile(temp.newFile()));
+    fs.add(new DefaultInputFile("src/Baz.java").setLanguage("java").setFile(temp.newFile()));
+
+    fs.inputFile(FilePredicates.all());
+  }
+
+  @Test
+  public void input_file_supports_non_indexed_predicates() throws Exception {
+    DefaultFileSystem fs = new DefaultFileSystem();
+    fs.add(new DefaultInputFile("src/Bar.java").setLanguage("java").setFile(temp.newFile()));
+
+    // it would fail if more than one java file
+    assertThat(fs.inputFile(FilePredicates.hasLanguage("java"))).isNotNull();
+  }
+}