Adds support for seed hash.

README.md

@@ -47,6 +47,13 @@ new WireMockServer(wireMockConfig().extensions(RandomExtension.class));
 
 This will generate random first names in the `en-US` locale for every request.
 
+You can optionally add the `seed` parameter to generate the same value for the same seed:
+
+{% raw %}
+```handlebars
+{{ random 'Name.first_name' seed=1234 }}
+```
+%}
 
 ### Technical notes
 This library brings `net.datafaker:datafaker` as transitive dependency, which may result in conflicts at building time. 

src/main/java/org/wiremock/RandomHelper.java

@@ -2,13 +2,16 @@
 
 import com.github.jknack.handlebars.Options;
 import com.github.tomakehurst.wiremock.extension.responsetemplating.helpers.HandlebarsHelper;
+import java.util.Random;
 import net.datafaker.Faker;
 
 /*
  * Author: Shreya Agarwal
  */
 public class RandomHelper extends HandlebarsHelper<Object> {
 
+  private static final String SEED_HASH = "seed";
+
   private final Faker faker;
 
   public RandomHelper() {
@@ -17,13 +20,18 @@ public RandomHelper() {
 
   @Override
   public Object apply(Object context, Options options) {
+
+    // Use a seeded Faker if seed hash exists
+    final var seedOption = options.hash(SEED_HASH);
+    var myFaker = seedOption == null ? faker : new Faker(new Random(seedOption.hashCode()));
+
     try {
       // Used the `expression` method instead of `resolve` as the
       // resolve method is not able to resolve nested references in the yml files. For example, in
       // the resource file for en-US, `address.full_address` wasn't resolving because of the
       // `#{street_address}` nested reference, but `address.postcode_by_state.AL` would work fine.
       // `expression` is able to handle all cases.
-      return faker.expression("#{" + context + "}");
+      return myFaker.expression("#{" + context + "}");
     } catch (RuntimeException e) {
       return handleError("Unable to evaluate the expression " + context, e);
     }

src/test/java/org/wiremock/RandomHelperTest.java

@@ -6,6 +6,7 @@
 import com.github.tomakehurst.wiremock.extension.responsetemplating.helpers.HandlebarsHelperTestBase;
 import java.io.IOException;
 import java.lang.reflect.Field;
+import java.util.Map;
 import java.util.Random;
 import net.datafaker.Faker;
 import org.junit.jupiter.api.BeforeEach;
@@ -40,4 +41,16 @@ public void returnsRandomValue(int seed, String expression, String expected) thr
     String actual = renderHelperValue(helper, expression);
     assertThat(actual, is(expected));
   }
+
+  @ParameterizedTest
+  @CsvSource(
+      value = {
+        "1, Donny",
+        "toto, Ethan",
+      })
+  public void rendersSeededRandomValue(Object seed, String expected) throws IOException {
+    final var actual = helper.apply("Name.firstName", createOptions(Map.of("seed", seed)));
+
+    assertThat(actual, is(expected));
+  }
 }