Add a convenient method to DistributionMetricSubject

Currently to assert that a given Metric<Distribution> as a certain distribution for some labels, the caller needs to manually create an ImmutableDistribution and pass it to #hasValueForLabels method. With this change, an ImmutableSet of data points can be passed to #hasDataSetForLabels method.

Also switched to use expectThrow backport from JUnit 4.13.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=173544521

java/google/registry/monitoring/metrics/contrib/AbstractMetricSubject.java

@@ -107,7 +107,7 @@ abstract class AbstractMetricSubject<T, S extends AbstractMetricSubject<T, S>>
     }
     if (!metricPoint.value().equals(value)) {
       failWithBadResults(
-          String.format("has a value of %s for labels", value),
+          String.format("has a value of %s for labels", getMessageRepresentation(value)),
           Joiner.on(':').join(labels),
           "has a value of",
           getMessageRepresentation(metricPoint.value()));

java/google/registry/monitoring/metrics/contrib/DistributionMetricSubject.java

@@ -16,12 +16,17 @@ package google.registry.monitoring.metrics.contrib;
 
 import static com.google.common.truth.Truth.assertAbout;
 
+import com.google.common.base.Joiner;
 import com.google.common.collect.BoundType;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Range;
 import com.google.common.truth.FailureMetadata;
 import google.registry.monitoring.metrics.Distribution;
+import google.registry.monitoring.metrics.ImmutableDistribution;
 import google.registry.monitoring.metrics.Metric;
 import google.registry.monitoring.metrics.MetricPoint;
+import google.registry.monitoring.metrics.MutableDistribution;
 import java.util.Map;
 import javax.annotation.Nullable;
 
@@ -36,6 +41,8 @@ import javax.annotation.Nullable;
  *       .hasNoOtherValues();
  *   assertThat(myDistributionMetric)
  *       .doesNotHaveAnyValueForLabels("label1", "label2");
+ *   assertThat(myDistributionMetric)
+ *       .hasDataSetForLabels(ImmutableSet.of(data1, data2, data3), "label1", "label2");
  * </pre>
  *
  * <p>The assertions treat an empty distribution as no value at all. This is not how the data is
@@ -94,4 +101,25 @@ public final class DistributionMetricSubject
     sb.append('}');
     return sb.toString();
   }
+
+  /**
+   * Asserts that the distribution for the given label can be constructed from the given data set.
+   *
+   * <p>Note that this only tests that the distribution has the same binned histogram as it would if
+   * it had recorded the specified data points. It could have in fact collected different data
+   * points that resulted in the same histogram, but that information is lost to us and cannot be
+   * tested.
+   */
+  public And<DistributionMetricSubject> hasDataSetForLabels(
+      ImmutableSet<? extends Number> dataSet, String... labels) {
+    ImmutableList<MetricPoint<Distribution>> metricPoints = actual().getTimestampedValues();
+    if (metricPoints.isEmpty()) {
+      failWithBadResults(
+          "has a distribution for labels", Joiner.on(':').join(labels), "has", "no values");
+    }
+    MutableDistribution targetDistribution =
+        new MutableDistribution(metricPoints.get(0).value().distributionFitter());
+    dataSet.forEach(data -> targetDistribution.add(data.doubleValue()));
+    return hasValueForLabels(ImmutableDistribution.copyOf(targetDistribution), labels);
+  }
 }

javatests/google/registry/monitoring/metrics/contrib/BUILD

@@ -13,6 +13,7 @@ java_library(
     deps = [
         "//java/google/registry/monitoring/metrics",
         "//java/google/registry/monitoring/metrics/contrib",
+        "//javatests/google/registry/testing",
         "@com_google_guava",
         "@com_google_truth",
         "@com_google_truth_extensions_truth_java8_extension",

javatests/google/registry/monitoring/metrics/contrib/DistributionMetricSubjectTest.java

@@ -15,9 +15,8 @@
 package google.registry.monitoring.metrics.contrib;
 
 import static com.google.common.truth.Truth.assertThat;
-import static com.google.common.truth.Truth8.assertThat;
 import static google.registry.monitoring.metrics.contrib.DistributionMetricSubject.assertThat;
-import static org.junit.Assert.fail;
+import static google.registry.testing.JUnitBackports.expectThrows;
 
 import com.google.common.collect.ImmutableSet;
 import google.registry.monitoring.metrics.EventMetric;
@@ -54,17 +53,15 @@ public class DistributionMetricSubjectTest {
 
   @Test
   public void testWrongNumberOfLabels_fails() {
-    try {
-      assertThat(metric).hasAnyValueForLabels("Domestic");
-      fail("Expected assertion error");
-    } catch (AssertionError e) {
-      assertThat(e)
-          .hasMessageThat()
-          .isEqualTo(
-              "Not true that </test/event/sheep> has a value for labels <Domestic>."
-              + " It has labeled values <[Bighorn:Blue =>"
-              + " {[4.0..16.0)=1}, Domestic:Green => {[1.0..4.0)=1}]>");
-    }
+    AssertionError e =
+        expectThrows(
+            AssertionError.class, () -> assertThat(metric).hasAnyValueForLabels("Domestic"));
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/sheep> has a value for labels <Domestic>."
+                + " It has labeled values <[Bighorn:Blue =>"
+                + " {[4.0..16.0)=1}, Domestic:Green => {[1.0..4.0)=1}]>");
   }
 
   @Test
@@ -89,33 +86,104 @@ public class DistributionMetricSubjectTest {
 
   @Test
   public void testDoesNotHaveValueForLabels_failure() {
-    try {
-      assertThat(metric).doesNotHaveAnyValueForLabels("Domestic", "Green");
-      fail("Expected assertion error");
-    } catch (AssertionError e) {
-      assertThat(e)
-          .hasMessageThat()
-          .isEqualTo(
-              "Not true that </test/event/sheep> has no value for labels <Domestic:Green>."
-              + " It has a value of <{[1.0..4.0)=1}>");
-    }
+    AssertionError e =
+        expectThrows(
+            AssertionError.class,
+            () -> assertThat(metric).doesNotHaveAnyValueForLabels("Domestic", "Green"));
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/sheep> has no value for labels <Domestic:Green>."
+                + " It has a value of <{[1.0..4.0)=1}>");
   }
 
   @Test
   public void testUnexpectedValue_failure() {
-    try {
-      assertThat(metric)
-          .hasAnyValueForLabels("Domestic", "Green")
-          .and()
-          .hasNoOtherValues();
-      fail("Expected assertion error");
-    } catch (AssertionError e) {
-      assertThat(e)
-          .hasMessageThat()
-          .isEqualTo(
-              "Not true that </test/event/sheep> has <no other nondefault values>."
-              + " It has labeled values <[Bighorn:Blue =>"
-              + " {[4.0..16.0)=1}, Domestic:Green => {[1.0..4.0)=1}]>");
-    }
+    AssertionError e =
+        expectThrows(
+            AssertionError.class,
+            () ->
+                assertThat(metric)
+                    .hasAnyValueForLabels("Domestic", "Green")
+                    .and()
+                    .hasNoOtherValues());
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/sheep> has <no other nondefault values>."
+                + " It has labeled values <[Bighorn:Blue =>"
+                + " {[4.0..16.0)=1}, Domestic:Green => {[1.0..4.0)=1}]>");
+  }
+
+  @Test
+  public void testExpectedDataSet_success() {
+    metric.record(7.5, "Domestic", "Green");
+    assertThat(metric).hasDataSetForLabels(ImmutableSet.of(2.5, 7.5), "Domestic", "Green");
+  }
+
+  @Test
+  public void testExpectedDataSetsChained_success() {
+    metric.record(7.5, "Domestic", "Green");
+    assertThat(metric)
+        .hasDataSetForLabels(ImmutableSet.of(2.5, 7.5), "Domestic", "Green")
+        .and()
+        .hasDataSetForLabels(ImmutableSet.of(10), "Bighorn", "Blue")
+        .and()
+        .hasNoOtherValues();
+  }
+
+  @Test
+  public void testUnexpectedDataSet_failure() {
+    AssertionError e =
+        expectThrows(
+            AssertionError.class,
+            () ->
+                assertThat(metric)
+                    .hasDataSetForLabels(ImmutableSet.of(2.5, 7.5), "Domestic", "Green"));
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/sheep> has a value of"
+                + " {[1.0..4.0)=1,[4.0..16.0)=1} for labels <Domestic:Green>."
+                + " It has a value of <{[1.0..4.0)=1}>");
+  }
+
+  @Test
+  public void testNonExistentLabels_failure() {
+    AssertionError e =
+        expectThrows(
+            AssertionError.class,
+            () ->
+                assertThat(metric)
+                    .hasDataSetForLabels(ImmutableSet.of(2.5, 7.5), "Domestic", "Blue"));
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/sheep> has a value for labels <Domestic:Blue>."
+                + " It has labeled values <[Bighorn:Blue => {[4.0..16.0)=1},"
+                + " Domestic:Green => {[1.0..4.0)=1}]>");
+  }
+
+  @Test
+  public void testEmptyMetric_failure() {
+    EventMetric emptyMetric =
+        MetricRegistryImpl.getDefault()
+            .newEventMetric(
+                "/test/event/goat",
+                "Sheep Latency",
+                "sheeplatency",
+                LABEL_DESCRIPTORS,
+                EventMetric.DEFAULT_FITTER);
+    AssertionError e =
+        expectThrows(
+            AssertionError.class,
+            () ->
+                assertThat(emptyMetric)
+                    .hasDataSetForLabels(ImmutableSet.of(2.5, 7.5), "Domestic", "Blue"));
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Not true that </test/event/goat> has a distribution for labels <Domestic:Blue>."
+                + " It has <no values>");
   }
 }