SONAR-6730 Measure computer should allowed no Input metrics

For instance, when a measure computer needs only issues to compute measures, it won't declare any input metrics

2 files changed, 64 insertions, 25 deletions

diff --git a/server/sonar-server/src/main/java/org/sonar/server/computation/measure/api/MeasureComputerImpl.java b/server/sonar-server/src/main/java/org/sonar/server/computation/measure/api/MeasureComputerImpl.java
index 02ac2759a52..1712950e7a0 100644
--- a/server/sonar-server/src/main/java/org/sonar/server/computation/measure/api/MeasureComputerImpl.java
+++ b/server/sonar-server/src/main/java/org/sonar/server/computation/measure/api/MeasureComputerImpl.java
@@ -22,9 +22,11 @@ package org.sonar.server.computation.measure.api;
 
 import com.google.common.collect.ImmutableSet;
 import java.util.Set;
+import javax.annotation.Nullable;
 import org.sonar.api.ce.measure.MeasureComputer;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.requireNonNull;
 
 public class MeasureComputerImpl implements MeasureComputer {
 
@@ -88,41 +90,57 @@ public class MeasureComputerImpl implements MeasureComputer {
 
   public static class MeasureComputerBuilderImpl implements MeasureComputerBuilder {
 
-    private String[] inputMetricKeys;
+    private String[] inputMetricKeys = new String[] {};
     private String[] outputMetrics;
     private Implementation measureComputerImplementation;
 
     @Override
     public MeasureComputerBuilder setInputMetrics(String... inputMetrics) {
-      checkArgument(inputMetrics != null && inputMetrics.length > 0, "At least one input metric must be defined");
-      this.inputMetricKeys = inputMetrics;
+      this.inputMetricKeys = validateInputMetricKeys(inputMetrics);
       return this;
     }
 
     @Override
     public MeasureComputerBuilder setOutputMetrics(String... outputMetrics) {
-      checkArgument(outputMetrics != null && outputMetrics.length > 0, "At least one output metric must be defined");
-      this.outputMetrics = outputMetrics;
+      this.outputMetrics = validateOutputMetricKeys(outputMetrics);
       return this;
     }
 
     @Override
     public MeasureComputerBuilder setImplementation(Implementation impl) {
-      checkImplementation(impl);
-      this.measureComputerImplementation = impl;
+      this.measureComputerImplementation = validateImplementation(impl);
       return this;
     }
 
     @Override
     public MeasureComputer build() {
-      checkArgument(this.inputMetricKeys != null, "At least one input metric must be defined");
-      checkArgument(this.outputMetrics != null, "At least one output metric must be defined");
-      checkImplementation(this.measureComputerImplementation);
+      validateInputMetricKeys(this.inputMetricKeys);
+      validateOutputMetricKeys(this.outputMetrics);
+      validateImplementation(this.measureComputerImplementation);
       return new MeasureComputerImpl(this);
     }
 
-    private static void checkImplementation(Implementation impl) {
-      checkArgument(impl != null, "The implementation is missing");
+    private static String[] validateInputMetricKeys(@Nullable String[] inputMetrics) {
+      requireNonNull(inputMetrics, "Input metrics cannot be null");
+      checkNotNull(inputMetrics);
+      return inputMetrics;
+    }
+
+    private static String[] validateOutputMetricKeys(@Nullable String[] outputMetrics) {
+      checkArgument(outputMetrics != null && outputMetrics.length > 0, "At least one output metric must be defined");
+      checkNotNull(outputMetrics);
+      return outputMetrics;
+    }
+
+    private static Implementation validateImplementation(Implementation impl) {
+      return requireNonNull(impl, "The implementation is missing");
     }
   }
+
+  private static void checkNotNull(String[] metrics){
+    for (String metric : metrics) {
+      requireNonNull(metric, "Null metric is not allowed");
+    }
+  }
+
 }
diff --git a/server/sonar-server/src/test/java/org/sonar/server/computation/measure/api/MeasureComputerImplTest.java b/server/sonar-server/src/test/java/org/sonar/server/computation/measure/api/MeasureComputerImplTest.java
index a813d8efd65..98eb6b04987 100644
--- a/server/sonar-server/src/test/java/org/sonar/server/computation/measure/api/MeasureComputerImplTest.java
+++ b/server/sonar-server/src/test/java/org/sonar/server/computation/measure/api/MeasureComputerImplTest.java
@@ -75,20 +75,30 @@ public class MeasureComputerImplTest {
   }
 
   @Test
-  public void fail_with_IAE_when_no_input_metrics() throws Exception {
-    thrown.expect(IllegalArgumentException.class);
-    thrown.expectMessage("At least one input metric must be defined");
+  public void input_metrics_can_be_empty() throws Exception {
+    MeasureComputer measureComputer = new MeasureComputerImpl.MeasureComputerBuilderImpl()
+      .setInputMetrics()
+      .setOutputMetrics("comment_density_1", "comment_density_2")
+      .setImplementation(DEFAULT_MEASURE_COMPUTER_IMPLEMENTATION)
+      .build();
 
-    new MeasureComputerImpl.MeasureComputerBuilderImpl()
+    assertThat(measureComputer.getInputMetrics()).isEmpty();
+  }
+
+  @Test
+  public void input_metrics_is_empty_when_not_set() throws Exception {
+    MeasureComputer measureComputer = new MeasureComputerImpl.MeasureComputerBuilderImpl()
       .setOutputMetrics("comment_density_1", "comment_density_2")
       .setImplementation(DEFAULT_MEASURE_COMPUTER_IMPLEMENTATION)
       .build();
+
+    assertThat(measureComputer.getInputMetrics()).isEmpty();
   }
 
   @Test
-  public void fail_with_IAE_when_null_input_metrics() throws Exception {
-    thrown.expect(IllegalArgumentException.class);
-    thrown.expectMessage("At least one input metric must be defined");
+  public void fail_with_NPE_when_null_input_metrics() throws Exception {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("Input metrics cannot be null");
 
     new MeasureComputerImpl.MeasureComputerBuilderImpl()
       .setInputMetrics(null)
@@ -97,12 +107,12 @@ public class MeasureComputerImplTest {
   }
 
   @Test
-  public void fail_with_IAE_with_empty_input_metrics() throws Exception {
-    thrown.expect(IllegalArgumentException.class);
-    thrown.expectMessage("At least one input metric must be defined");
+  public void fail_with_NPE_when_one_input_metric_is_null() throws Exception {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("Null metric is not allowed");
 
     new MeasureComputerImpl.MeasureComputerBuilderImpl()
-      .setInputMetrics()
+      .setInputMetrics("ncloc", null)
       .setOutputMetrics("comment_density_1", "comment_density_2")
       .setImplementation(DEFAULT_MEASURE_COMPUTER_IMPLEMENTATION);
   }
@@ -130,6 +140,17 @@ public class MeasureComputerImplTest {
   }
 
   @Test
+  public void fail_with_NPE_when_one_output_metric_is_null() throws Exception {
+    thrown.expect(NullPointerException.class);
+    thrown.expectMessage("Null metric is not allowed");
+
+    new MeasureComputerImpl.MeasureComputerBuilderImpl()
+      .setInputMetrics("ncloc", "comment")
+      .setOutputMetrics("comment_density_1", null)
+      .setImplementation(DEFAULT_MEASURE_COMPUTER_IMPLEMENTATION);
+  }
+
+  @Test
   public void fail_with_IAE_with_empty_output_metrics() throws Exception {
     thrown.expect(IllegalArgumentException.class);
     thrown.expectMessage("At least one output metric must be defined");
@@ -142,7 +163,7 @@ public class MeasureComputerImplTest {
 
   @Test
   public void fail_with_IAE_when_no_implementation() throws Exception {
-    thrown.expect(IllegalArgumentException.class);
+    thrown.expect(NullPointerException.class);
     thrown.expectMessage("The implementation is missing");
 
     new MeasureComputerImpl.MeasureComputerBuilderImpl()
@@ -153,7 +174,7 @@ public class MeasureComputerImplTest {
 
   @Test
   public void fail_with_IAE_when_null_implementation() throws Exception {
-    thrown.expect(IllegalArgumentException.class);
+    thrown.expect(NullPointerException.class);
     thrown.expectMessage("The implementation is missing");
 
     new MeasureComputerImpl.MeasureComputerBuilderImpl()