Building response with log normal delays

Author: tommysitu

docs/pages/corefunctionality/dsl.rst

@@ -52,13 +52,22 @@ Per-request delay can be set as follows:
 
 .. code-block:: java
 
+    // Fixed delay
     SimulationSource.dsl(
         service("www.not-so-slow-service.com")
             .get("/api/bookings")
             .willReturn(success().withFixedDelay(1, TimeUnit.SECONDS))
         )
     )
 
+    // Log Normal random delay
+    SimulationSource.dsl(
+        service("www.not-so-slow-service.com")
+            .get("/api/bookings")
+            .willReturn(success().withLogNormalDelay(2, 1, TimeUnit.SECONDS))
+        )
+    )
+
 
 Request/response body conversion
 --------------------------------

src/main/java/io/specto/hoverfly/junit/core/model/LogNormalDelay.java

@@ -0,0 +1,42 @@
+package io.specto.hoverfly.junit.core.model;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class LogNormalDelay {
+
+    private final int min;
+    private final int max;
+    private final int mean;
+    private final int median;
+
+    @JsonCreator
+    public LogNormalDelay(
+            @JsonProperty("min") int min,
+            @JsonProperty("max") int max,
+            @JsonProperty("mean") int mean,
+            @JsonProperty("median") int median) {
+        this.min = min;
+        this.max = max;
+        this.mean = mean;
+        this.median = median;
+    }
+
+    public int getMin() {
+        return min;
+    }
+
+    public int getMax() {
+        return max;
+    }
+
+    public int getMean() {
+        return mean;
+    }
+
+    public int getMedian() {
+        return median;
+    }
+}

src/main/java/io/specto/hoverfly/junit/core/model/Response.java

@@ -19,6 +19,7 @@
 import org.apache.commons.lang3.builder.EqualsBuilder;
 import org.apache.commons.lang3.builder.HashCodeBuilder;
 import org.apache.commons.lang3.builder.ToStringBuilder;
+import sun.rmi.runtime.Log;
 
 import java.util.List;
 import java.util.Map;
@@ -34,18 +35,19 @@ public class Response {
     private final Map<String, String> transitionsState;
     private final List<String> removesState;
     private final Integer fixedDelay;
-
+    private final LogNormalDelay logNormalDelay;
 
     @JsonCreator
     public Response(
-        @JsonProperty("status") Integer status,
-        @JsonProperty("body") String body,
-        @JsonProperty("encodedBody") boolean encodedBody,
-        @JsonProperty("templated") boolean templated,
-        @JsonProperty("headers") Map<String, List<String>> headers,
-        @JsonProperty("transitionsState") Map<String, String> transitionsState,
-        @JsonProperty("removesState") List<String> removesState,
-        @JsonProperty("fixedDelay") Integer fixedDelay) {
+            @JsonProperty("status") Integer status,
+            @JsonProperty("body") String body,
+            @JsonProperty("encodedBody") boolean encodedBody,
+            @JsonProperty("templated") boolean templated,
+            @JsonProperty("headers") Map<String, List<String>> headers,
+            @JsonProperty("transitionsState") Map<String, String> transitionsState,
+            @JsonProperty("removesState") List<String> removesState,
+            @JsonProperty("fixedDelay") Integer fixedDelay,
+            @JsonProperty("logNormalDelay") LogNormalDelay logNormalDelay) {
         this.status = status;
         this.body = body;
         this.encodedBody = encodedBody;
@@ -54,6 +56,7 @@ public Response(
         this.transitionsState = transitionsState;
         this.removesState = removesState;
         this.fixedDelay = fixedDelay;
+        this.logNormalDelay = logNormalDelay;
     }
 
     public Integer getStatus() {
@@ -89,6 +92,10 @@ public Integer getFixedDelay() {
         return fixedDelay;
     }
 
+    public LogNormalDelay getLogNormalDelay() {
+        return logNormalDelay;
+    }
+
     static class Builder {
         private Integer status;
         private String body;
@@ -98,6 +105,7 @@ static class Builder {
         private Map<String, String> transitionsState;
         private List<String> removesState;
         private Integer fixedDelay;
+        private LogNormalDelay logNormalDelay;
 
         Builder status(int status) {
             this.status = status;
@@ -139,8 +147,13 @@ Builder fixedDelay(int fixedDelay) {
             return this;
         }
 
+        Builder logNormalDelay(int min, int max, int mean, int median) {
+            this.logNormalDelay = new LogNormalDelay(min, max, mean, median);
+            return this;
+        }
+
         Response build() {
-            return new Response(status, body, encodedBody, templated, headers, transitionsState, removesState, fixedDelay);
+            return new Response(status, body, encodedBody, templated, headers, transitionsState, removesState, fixedDelay, logNormalDelay);
         }
     }
 

src/main/java/io/specto/hoverfly/junit/dsl/ResponseBuilder.java

@@ -12,6 +12,7 @@
  */
 package io.specto.hoverfly.junit.dsl;
 
+import io.specto.hoverfly.junit.core.model.LogNormalDelay;
 import io.specto.hoverfly.junit.core.model.Response;
 
 import java.util.ArrayList;
@@ -37,7 +38,7 @@ public class ResponseBuilder {
     private final List<String> removesState = new ArrayList<>();
 
     private int fixedDelay;
-    private TimeUnit fixedDelayTimeUnit;
+    private LogNormalDelay logNormalDelay;
 
     // Deprecated: For global delay settings
     private int delay;
@@ -112,8 +113,7 @@ public ResponseBuilder andRemoveState(final String stateToRemove) {
      * @return the response
      */
     Response build() {
-        int fixedDelayInMillis = fixedDelayTimeUnit == null ? 0 : (int) fixedDelayTimeUnit.toMillis(fixedDelay);
-        return new Response(status, body, false, templated, headers, transitionsState, removesState, fixedDelayInMillis);
+        return new Response(status, body, false, templated, headers, transitionsState, removesState, fixedDelay, logNormalDelay);
     }
 
     public ResponseBuilder body(final HttpBodyConverter httpBodyConverter) {
@@ -128,9 +128,53 @@ public ResponseBuilder disableTemplating() {
         return this;
     }
 
+
+    /**
+     * Set fixed delay for the request-response pair
+     * @param delay amount of delay
+     * @param delayTimeUnit time unit of delay (e.g. SECONDS)
+     * @return the {@link ResponseBuilder for further customizations}
+     */
     public ResponseBuilder withFixedDelay(int delay, TimeUnit delayTimeUnit) {
-        fixedDelay = delay;
-        fixedDelayTimeUnit = delayTimeUnit;
+        fixedDelay = (int) delayTimeUnit.toMillis(delay);
+        return this;
+    }
+
+    /**
+     * Set Log Normal delay for the request-response pair. The delay value will be generated randomly based on the distribution
+     * which is defined by 2 parameters μ and σ. We will compute these parameters from the mean and median of a server response time.
+     * You can typically find these values in your monitoring of the production server.
+     * @param mean mean value of the delays to simulate
+     * @param median median value of the delays to simulate
+     * @param delayTimeUnit time unit of delay (e.g. SECONDS)
+     * @return the {@link ResponseBuilder for further customizations}
+     */
+    public ResponseBuilder withLogNormalDelay(int mean, int median, TimeUnit delayTimeUnit) {
+        logNormalDelay = new LogNormalDelay(
+                0,
+                0,
+                (int) delayTimeUnit.toMillis(mean),
+                (int) delayTimeUnit.toMillis(median));
+        return this;
+    }
+
+    /**
+     * Set Log Normal delay for the request-response pair. The delay value will be generated randomly based on the distribution
+     * which is defined by 2 parameters μ and σ. We will compute these parameters from the mean and median of a server response time.
+     * You can typically find these values in your monitoring of the production server.
+     * @param mean mean value of the delays to simulate
+     * @param median median value of the delays to simulate
+     * @param min lower bound of the delays
+     * @param max upper bound of the delays
+     * @param delayTimeUnit time unit of delay (e.g. SECONDS)
+     * @return the {@link ResponseBuilder for further customizations}
+     */
+    public ResponseBuilder withLogNormalDelay(int mean, int median, int min, int max, TimeUnit delayTimeUnit) {
+        logNormalDelay = new LogNormalDelay(
+                (int) delayTimeUnit.toMillis(min),
+                (int) delayTimeUnit.toMillis(max),
+                (int) delayTimeUnit.toMillis(mean),
+                (int) delayTimeUnit.toMillis(median));
         return this;
     }
 

src/test/java/io/specto/hoverfly/junit/dsl/StubServiceBuilderTest.java

@@ -3,10 +3,8 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.Iterables;
-import io.specto.hoverfly.junit.core.model.Request;
-import io.specto.hoverfly.junit.core.model.RequestFieldMatcher;
-import io.specto.hoverfly.junit.core.model.RequestResponsePair;
-import io.specto.hoverfly.junit.core.model.Response;
+import io.specto.hoverfly.junit.core.model.*;
+
 import java.util.concurrent.TimeUnit;
 import org.apache.commons.lang3.builder.EqualsBuilder;
 import org.apache.commons.lang3.builder.HashCodeBuilder;
@@ -554,6 +552,32 @@ public void shouldBeAbleToSetFixedDelay() {
         assertThat(pair.getResponse().getFixedDelay()).isEqualTo(10000);
     }
 
+    @Test
+    public void shouldBeAbleToSetLogNormalRandomDelay() {
+
+        final RequestResponsePair pair = service("https://www.my-test.com")
+                .get("/")
+                .willReturn(response().withLogNormalDelay(3, 4, TimeUnit.SECONDS))
+                .getRequestResponsePairs()
+                .iterator().next();
+
+        assertThat(pair.getResponse().getLogNormalDelay())
+                .isEqualToComparingFieldByField(new LogNormalDelay(0, 0, 3000, 4000));
+    }
+
+    @Test
+    public void shouldBeAbleToSetLogNormalRandomDelayWithMinAndMax() {
+
+        final RequestResponsePair pair = service("https://www.my-test.com")
+                .get("/")
+                .willReturn(response().withLogNormalDelay(3, 4, 1, 5, TimeUnit.SECONDS))
+                .getRequestResponsePairs()
+                .iterator().next();
+
+        assertThat(pair.getResponse().getLogNormalDelay())
+                .isEqualToComparingFieldByField(new LogNormalDelay(1000, 5000, 3000, 4000));
+    }
+
     @Test
     public void shouldSetDefaultValuesForResponse() {
 
@@ -564,14 +588,15 @@ public void shouldSetDefaultValuesForResponse() {
             .iterator().next()
             .getResponse();
 
-        assertThat(response.getFixedDelay()).isEqualTo(0);
         assertThat(response.getStatus()).isEqualTo(200);
         assertThat(response.getBody()).isEmpty();
         assertThat(response.getHeaders()).isEmpty();
         assertThat(response.getTransitionsState()).isEmpty();
         assertThat(response.getRemovesState()).isEmpty();
         assertThat(response.isEncodedBody()).isFalse();
         assertThat(response.isTemplated()).isTrue();
+        assertThat(response.getFixedDelay()).isEqualTo(0);
+        assertThat(response.getLogNormalDelay()).isNull();
     }
 
     private void assertExactMatcherForMethod(RequestMatcherBuilder builder, String method) {