SONAR-6620 current project can actually have no QualityGate at all

in which case, no QualityGate measure must be created nor any measure have its QualityGateStatus be updated

server/sonar-server/src/main/java/org/sonar/server/computation/qualitygate/MutableQualityGateHolder.java

@@ -30,7 +30,14 @@ public interface MutableQualityGateHolder extends QualityGateHolder {
    * @param qualityGate a {@link Component}, can not be {@code null}
    *
    * @throws NullPointerException if {@code qualityGate} is {@code null}
-   * @throws IllegalStateException if the quality gate has already been set
+   * @throws IllegalStateException if the holder has already been initialized
    */
   void setQualityGate(QualityGate qualityGate);
+
+  /**
+   * Sets that there is no quality gate for the project of the currently processed {@link ReportQueue.Item}.
+   *
+   * @throws IllegalStateException if the holder has already been initialized
+   */
+  void setNoQualityGate();
 }

server/sonar-server/src/main/java/org/sonar/server/computation/qualitygate/QualityGateHolder.java

@@ -19,13 +19,14 @@
  */
 package org.sonar.server.computation.qualitygate;
 
+import com.google.common.base.Optional;
 import org.sonar.server.computation.ReportQueue;
 
 public interface QualityGateHolder {
   /**
-   * The QualityGate for the project of the current {@link ReportQueue.Item}.
+   * The QualityGate for the project of the current {@link ReportQueue.Item} if there is any.
    *
-   * @throws IllegalStateException if the holder is empty (ie. there is no quality gate yet)
+   * @throws IllegalStateException if the holder has not been initialized (ie. we don't know yet what is the QualityGate)
    */
-  QualityGate getQualityGate();
+  Optional<QualityGate> getQualityGate();
 }

server/sonar-server/src/main/java/org/sonar/server/computation/qualitygate/QualityGateHolderImpl.java

@@ -19,29 +19,44 @@
  */
 package org.sonar.server.computation.qualitygate;
 
-import java.util.Objects;
+import com.google.common.base.Optional;
 import javax.annotation.CheckForNull;
 
+import static com.google.common.base.Optional.absent;
+import static com.google.common.base.Optional.of;
+import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
+
 public class QualityGateHolderImpl implements MutableQualityGateHolder {
+  private boolean initialized = false;
   @CheckForNull
-  private QualityGate qualityGate;
+  private Optional<QualityGate> qualityGate;
 
   @Override
   public void setQualityGate(QualityGate qualityGate) {
     // fail fast
-    Objects.requireNonNull(qualityGate);
+    requireNonNull(qualityGate);
+    checkNotInitialized();
+
+    this.initialized = true;
+    this.qualityGate = of(qualityGate);
+  }
+
+  @Override
+  public void setNoQualityGate() {
+    checkNotInitialized();
+
+    this.initialized = true;
+    this.qualityGate = absent();
+  }
 
-    if (this.qualityGate != null) {
-      throw new IllegalStateException("QualityGate can be set only once");
-    }
-    this.qualityGate = qualityGate;
+  private void checkNotInitialized() {
+    checkState(!initialized, "QualityGateHolder can be initialized only once");
   }
 
   @Override
-  public QualityGate getQualityGate() {
-    if (qualityGate == null) {
-      throw new IllegalStateException("QualityGate has not been set yet");
-    }
+  public Optional<QualityGate> getQualityGate() {
+    checkState(initialized, "QualityGate has not been set yet");
     return qualityGate;
   }
 }

server/sonar-server/src/main/java/org/sonar/server/computation/step/QualityGateLoadingStep.java

@@ -19,7 +19,7 @@
  */
 package org.sonar.server.computation.step;
 
-import java.util.Collections;
+import com.google.common.base.Optional;
 import org.apache.commons.lang.StringUtils;
 import org.sonar.api.config.Settings;
 import org.sonar.api.utils.log.Logger;
@@ -29,7 +29,6 @@
 import org.sonar.server.computation.component.DepthTraversalTypeAwareVisitor;
 import org.sonar.server.computation.component.ProjectSettingsRepository;
 import org.sonar.server.computation.component.TreeRootHolder;
-import org.sonar.server.computation.qualitygate.Condition;
 import org.sonar.server.computation.qualitygate.MutableQualityGateHolder;
 import org.sonar.server.computation.qualitygate.QualityGate;
 import org.sonar.server.computation.qualitygate.QualityGateService;
@@ -45,7 +44,6 @@ public class QualityGateLoadingStep implements ComputationStep {
   private static final Logger LOGGER = Loggers.get(QualityGateLoadingStep.class);
 
   private static final String PROPERTY_QUALITY_GATE = "sonar.qualitygate";
-  private static final QualityGate DEFAULT_QUALITY_GATE = new QualityGate("default Quality Gate", Collections.<Condition>emptyList());
 
   private final TreeRootHolder treeRootHolder;
   private final ProjectSettingsRepository projectSettingsRepository;
@@ -77,16 +75,23 @@ private void executeForProject(Component project) {
 
     if (qualityGateSetting == null || StringUtils.isBlank(qualityGateSetting)) {
       LOGGER.debug("No quality gate is configured for project " + projectKey);
-      qualityGateHolder.setQualityGate(DEFAULT_QUALITY_GATE);
+      qualityGateHolder.setNoQualityGate();
       return;
     }
 
     try {
-      long qualityGateId = Long.parseLong(qualityGateSetting.trim());
-      qualityGateHolder.setQualityGate(qualityGateService.findById(qualityGateId).or(DEFAULT_QUALITY_GATE));
+      long qualityGateId = Long.parseLong(qualityGateSetting);
+      Optional<QualityGate> qualityGate = qualityGateService.findById(qualityGateId);
+      if (qualityGate.isPresent()) {
+        qualityGateHolder.setQualityGate(qualityGate.get());
+      }
+      else {
+        qualityGateHolder.setNoQualityGate();
+      }
     } catch (NumberFormatException e) {
-      LOGGER.error(String.format("Unsupported value in property %s, using empty Quality Gate", PROPERTY_QUALITY_GATE));
-      qualityGateHolder.setQualityGate(DEFAULT_QUALITY_GATE);
+      throw new IllegalStateException(
+        String.format("Unsupported value (%s) in property %s", qualityGateSetting, PROPERTY_QUALITY_GATE),
+        e);
     }
   }
 

server/sonar-server/src/main/java/org/sonar/server/computation/step/QualityGateMeasuresStep.java

@@ -40,6 +40,7 @@
 import org.sonar.server.computation.qualitygate.ConditionEvaluator;
 import org.sonar.server.computation.qualitygate.EvaluationResult;
 import org.sonar.server.computation.qualitygate.EvaluationResultTextConverter;
+import org.sonar.server.computation.qualitygate.QualityGate;
 import org.sonar.server.computation.qualitygate.QualityGateHolder;
 
 import static org.sonar.server.computation.component.Component.Type.PROJECT;
@@ -85,9 +86,12 @@ public void visitProject(Component project) {
   private void executeForProject(Component project) {
     QualityGateDetailsDataBuilder builder = new QualityGateDetailsDataBuilder();
 
-    updateMeasures(project, qualityGateHolder.getQualityGate().getConditions(), builder);
+    Optional<QualityGate> qualityGate = qualityGateHolder.getQualityGate();
+    if (qualityGate.isPresent()) {
+      updateMeasures(project, qualityGate.get().getConditions(), builder);
 
-    addProjectMeasure(project, builder);
+      addProjectMeasure(project, builder);
+    }
   }
 
   private void updateMeasures(Component project, Set<Condition> conditions, QualityGateDetailsDataBuilder builder) {

server/sonar-server/src/test/java/org/sonar/server/computation/qualitygate/MutableQualityGateHolderRule.java

@@ -19,27 +19,25 @@
  */
 package org.sonar.server.computation.qualitygate;
 
-import java.util.Objects;
+import com.google.common.base.Optional;
 import org.junit.rules.ExternalResource;
 
 public class MutableQualityGateHolderRule extends ExternalResource implements MutableQualityGateHolder {
-  private QualityGate qualityGate;
+  private MutableQualityGateHolder delegate = new QualityGateHolderImpl();
 
   @Override
   public void setQualityGate(QualityGate qualityGate) {
-    Objects.requireNonNull(qualityGate);
-    if (this.qualityGate != null) {
-      throw new IllegalStateException("QualityGate can not be set more than once");
-    }
-    this.qualityGate = qualityGate;
+    delegate.setQualityGate(qualityGate);
   }
 
   @Override
-  public QualityGate getQualityGate() {
-    if (this.qualityGate == null) {
-      throw new IllegalStateException("QualityGate has not been set");
-    }
-    return qualityGate;
+  public void setNoQualityGate() {
+    delegate.setNoQualityGate();
+  }
+
+  @Override
+  public Optional<QualityGate> getQualityGate() {
+    return delegate.getQualityGate();
   }
 
   @Override
@@ -48,6 +46,6 @@ protected void after() {
   }
 
   public void reset() {
-    this.qualityGate = null;
+    this.delegate = new QualityGateHolderImpl();
   }
 }

server/sonar-server/src/test/java/org/sonar/server/computation/qualitygate/QualityGateHolderImplTest.java

@@ -23,6 +23,7 @@
 import org.junit.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.guava.api.Assertions.assertThat;
 
 public class QualityGateHolderImplTest {
 
@@ -52,7 +53,16 @@ public void getQualityGate_returns_QualityGate_set_by_setQualityGate() {
 
     holder.setQualityGate(QUALITY_GATE);
 
-    assertThat(holder.getQualityGate()).isSameAs(QUALITY_GATE);
+    assertThat(holder.getQualityGate().get()).isSameAs(QUALITY_GATE);
+  }
+
+  @Test
+  public void getQualityGate_returns_absent_if_holder_initialized_with_setNoQualityGate() {
+    QualityGateHolderImpl holder = new QualityGateHolderImpl();
+
+    holder.setNoQualityGate();
+
+    assertThat(holder.getQualityGate()).isAbsent();
   }
 
 }

server/sonar-server/src/test/java/org/sonar/server/computation/step/QualityGateLoadingStepTest.java

@@ -23,6 +23,7 @@
 import java.util.Collections;
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.sonar.api.config.Settings;
 import org.sonar.server.computation.batch.TreeRootHolderRule;
 import org.sonar.server.computation.component.Component;
@@ -34,15 +35,18 @@
 import org.sonar.server.computation.qualitygate.QualityGateService;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.guava.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.when;
 
 public class QualityGateLoadingStepTest {
   private static final String PROJECT_KEY = "project key";
-  public static final DumbComponent PROJECT_ALONE = DumbComponent.builder(Component.Type.PROJECT, 1).setKey(PROJECT_KEY).build();
+  private static final DumbComponent PROJECT_ALONE = DumbComponent.builder(Component.Type.PROJECT, 1).setKey(PROJECT_KEY).build();
 
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
   @Rule
   public TreeRootHolderRule treeRootHolder = new TreeRootHolderRule();
   @Rule
@@ -60,7 +64,7 @@ public void execute_sets_default_QualityGate_when_project_has_no_settings() {
 
     underTest.execute();
 
-    verifyDefaultQualityGateHasBeenSet();
+    verifyNoQualityGate();
 
     // verify only project is processed
     verify(projectSettingsRepository).getProjectSettings(PROJECT_KEY);
@@ -69,20 +73,13 @@ public void execute_sets_default_QualityGate_when_project_has_no_settings() {
 
   @Test
   public void execute_sets_default_QualityGate_when_property_value_is_not_a_long() {
-    verify_execute_sets_default_QualityGate_when_property_value_is_not_a_long("");
-    verify_execute_sets_default_QualityGate_when_property_value_is_not_a_long("  ");
-    verify_execute_sets_default_QualityGate_when_property_value_is_not_a_long(" 10 sds ");
-  }
+    expectedException.expect(IllegalStateException.class);
+    expectedException.expectMessage(String.format("Unsupported value (%s) in property sonar.qualitygate", "10 sds"));
 
-  private void verify_execute_sets_default_QualityGate_when_property_value_is_not_a_long(String value) {
     treeRootHolder.setRoot(PROJECT_ALONE);
-    when(projectSettingsRepository.getProjectSettings(PROJECT_KEY)).thenReturn(new Settings().setProperty("sonar.qualitygate", value));
+    when(projectSettingsRepository.getProjectSettings(PROJECT_KEY)).thenReturn(new Settings().setProperty("sonar.qualitygate", "10 sds"));
 
     underTest.execute();
-
-    verifyDefaultQualityGateHasBeenSet();
-
-    mutableQualityGateHolder.reset();
   }
 
   @Test
@@ -93,7 +90,7 @@ public void execute_sets_default_QualityGate_if_it_can_not_be_found_by_service()
 
     underTest.execute();
 
-    verifyDefaultQualityGateHasBeenSet();
+    verifyNoQualityGate();
   }
 
   @Test
@@ -106,12 +103,11 @@ public void execute_sets_QualityGate_if_it_can_be_found_by_service() {
 
     underTest.execute();
 
-    assertThat(mutableQualityGateHolder.getQualityGate()).isSameAs(qualityGate);
+    assertThat(mutableQualityGateHolder.getQualityGate().get()).isSameAs(qualityGate);
   }
 
-  private void verifyDefaultQualityGateHasBeenSet() {
-    assertThat(mutableQualityGateHolder.getQualityGate().getName()).isEqualTo("default Quality Gate");
-    assertThat(mutableQualityGateHolder.getQualityGate().getConditions()).isEmpty();
+  private void verifyNoQualityGate() {
+    assertThat(mutableQualityGateHolder.getQualityGate()).isAbsent();
   }
 
 }

server/sonar-server/src/test/java/org/sonar/server/computation/step/QualityGateMeasuresStepTest.java

@@ -112,6 +112,15 @@ public void no_measure_if_tree_has_no_project() {
     verifyNoMoreInteractions(measureRepository);
   }
 
+  @Test
+  public void no_measure_if_there_is_no_qualitygate() {
+    qualityGateHolder.setNoQualityGate();
+
+    underTest.execute();
+
+    verifyNoMoreInteractions(measureRepository);
+  }
+
   @Test
   public void new_measures_are_created_even_if_there_is_no_rawMeasure_for_metric_of_condition() {
     Condition equals2Condition = createEqualsCondition(INT_METRIC_1, "2", null);