Verify exception messages in tests (prometheus#566)

Improve test coverage and make refactorings more safe.

Signed-off-by: Stefan Birkner <mail@stefan-birkner.de>

Author: stefanbirkner

simpleclient/src/test/java/io/prometheus/client/CounterTest.java

@@ -1,17 +1,24 @@
 package io.prometheus.client;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.rules.ExpectedException.none;
 
 import java.util.ArrayList;
 import java.util.List;
+
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.Before;
+import org.junit.rules.ExpectedException;
 
 
 public class CounterTest {
   CollectorRegistry registry;
   Counter noLabels, labels;
 
+  @Rule
+  public final ExpectedException thrown = none();
+
   @Before
   public void setUp() {
     registry = new CollectorRegistry();
@@ -39,8 +46,10 @@ public void testIncrement() {
     assertEquals(8.0, noLabels.get(), .001);
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testNegativeIncrementFails() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Amount to increment must be non-negative.");
     noLabels.inc(-1);
   }
 

simpleclient/src/test/java/io/prometheus/client/HistogramTest.java

@@ -3,6 +3,7 @@
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.rules.ExpectedException.none;
 
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -11,14 +12,20 @@
 import java.util.concurrent.Callable;
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 
 public class HistogramTest {
 
   CollectorRegistry registry;
   Histogram noLabels, labels;
 
+
+  @Rule
+  public final ExpectedException thrown = none();
+
   @Before
   public void setUp() {
     registry = new CollectorRegistry();
@@ -166,8 +173,10 @@ public void testLabels() {
     assertEquals(3.0, getLabelsSum("b").doubleValue(), .001);
   }
 
-  @Test(expected=IllegalStateException.class)
+  @Test
   public void testLeLabelThrows() {
+    thrown.expect(IllegalStateException.class);
+    thrown.expectMessage("Histogram cannot have a label named 'le'.");
     Histogram.build().name("labels").help("help").labelNames("le").create();
   }
 

simpleclient/src/test/java/io/prometheus/client/SimpleCollectorTest.java

@@ -3,9 +3,12 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.rules.ExpectedException.none;
 
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.Before;
+import org.junit.rules.ExpectedException;
 
 
 public class SimpleCollectorTest {
@@ -14,6 +17,9 @@ public class SimpleCollectorTest {
   Gauge metric;
   Gauge noLabels;
 
+  @Rule
+  public final ExpectedException thrown = none();
+
   @Before
   public void setUp() {
     registry = new CollectorRegistry();
@@ -29,18 +35,24 @@ private Double getValueNoLabels() {
     return registry.getSampleValue("nolabels");
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testTooFewLabelsThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Incorrect number of labels.");
     metric.labels();
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testNullLabelThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Label cannot be null.");
     metric.labels(new String[]{null});
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testTooManyLabelsThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Incorrect number of labels.");
     metric.labels("a", "b");
   }
 
@@ -97,28 +109,39 @@ public void testNameIsConcatenated() {
     assertEquals("a_b_c", Gauge.build().name("c").subsystem("b").namespace("a").help("h").create().fullname);
   }
 
-  @Test(expected=IllegalStateException.class)
+  @Test
   public void testNameIsRequired() {
+    thrown.expect(IllegalStateException.class);
+    thrown.expectMessage("Name hasn't been set.");
     Gauge.build().help("h").create();
   }
 
-  @Test(expected=IllegalStateException.class)
+  @Test
   public void testHelpIsRequired() {
+    thrown.expect(IllegalStateException.class);
+    thrown.expectMessage("Help hasn't been set.");
     Gauge.build().name("c").create();
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testInvalidNameThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Invalid metric name: c'a");
     Gauge.build().name("c'a").create();
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testInvalidLabelNameThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Invalid metric label name: c:d");
     Gauge.build().name("a").labelNames("c:d").help("h").create();
   }
 
-  @Test(expected=IllegalArgumentException.class)
+  @Test
   public void testReservedLabelNameThrows() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage(
+            "Invalid metric label name, reserved for internal use: __name__");
     Gauge.build().name("a").labelNames("__name__").help("h").create();
   }
 

simpleclient_pushgateway/src/test/java/io/prometheus/client/exporter/PushGatewayTest.java

@@ -1,6 +1,7 @@
 package io.prometheus.client.exporter;
 
 
+import static org.junit.rules.ExpectedException.none;
 import static org.mockserver.model.HttpRequest.request;
 import static org.mockserver.model.HttpResponse.response;
 
@@ -13,11 +14,16 @@
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.mockserver.junit.MockServerRule;
 import org.mockserver.client.server.MockServerClient;
 
 public class PushGatewayTest {
 
+
+  @Rule
+  public final ExpectedException thrown = none();
+
   @Rule
   public MockServerRule mockServerRule = new MockServerRule(this);
   private MockServerClient mockServerClient;
@@ -70,13 +76,18 @@ public void testPush200Response() throws IOException {
     pg.push(registry, "j");
   }
 
-  @Test(expected=IOException.class)
+  @Test
   public void testNon202ResponseThrows() throws IOException {
     mockServerClient.when(
         request()
           .withMethod("PUT")
           .withPath("/metrics/job/j")
       ).respond(response().withStatusCode(500));
+    thrown.expect(IOException.class);
+    thrown.expectMessage(
+            "Response code from http://localhost:"
+                    + mockServerRule.getHttpPort()
+                    + "/metrics/job/j was 500");
     pg.push(registry, "j");
   }
 
@@ -223,13 +234,18 @@ public void testOldPushWithInstance() throws IOException {
     pg.push(registry, "j", "i");
   }
 
-  @Test(expected=IOException.class)
+  @Test
   public void testOldNon202ResponseThrows() throws IOException {
     mockServerClient.when(
         request()
           .withMethod("PUT")
           .withPath("/metrics/job/j/instance/i")
       ).respond(response().withStatusCode(500));
+    thrown.expect(IOException.class);
+    thrown.expectMessage(
+            "Response code from http://localhost:"
+                    + mockServerRule.getHttpPort()
+                    + "/metrics/job/j/instance/i was 500");
     pg.push(registry,"j", "i");
   }