Change default JSON serializer to use jackson instead of GSON. It allows ordered JSON serialization of maps

Author: andrebonna

pom.xml

@@ -51,9 +51,14 @@
 
     <dependencies>
         <dependency>
-            <groupId>com.google.code.gson</groupId>
-            <artifactId>gson</artifactId>
-            <version>2.8.5</version>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>2.9.8</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.9.8</version>
         </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>

src/main/java/io/github/jsonSnapshot/SnapshotMatcher.java

@@ -1,6 +1,12 @@
 package io.github.jsonSnapshot;
 
-import com.google.gson.GsonBuilder;
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.core.util.DefaultIndenter;
+import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
+import com.fasterxml.jackson.core.util.Separators;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import org.apache.commons.lang3.ArrayUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.assertj.core.util.Arrays;
@@ -89,8 +95,45 @@ public static Snapshot expect(Object firstObject, Object... others) {
         }
     }
 
-    private static Function<Object, String> defaultJsonFunction() {
-        return (object) -> new GsonBuilder().setPrettyPrinting().create().toJson(object);
+    static Function<Object, String> defaultJsonFunction() {
+
+        ObjectMapper objectMapper = buildObjectMapper();
+
+        DefaultPrettyPrinter pp = buildDefaultPrettyPrinter();
+
+        return (object) -> {
+            try {
+                return objectMapper.writer(pp).writeValueAsString(object);
+            } catch (Exception e) {
+                throw new SnapshotMatchException(e.getMessage());
+            }
+        };
+    }
+
+    private static DefaultPrettyPrinter buildDefaultPrettyPrinter() {
+        DefaultPrettyPrinter pp = new DefaultPrettyPrinter(""){
+            @Override
+            public DefaultPrettyPrinter withSeparators(Separators separators) {
+                this._separators = separators;
+                this._objectFieldValueSeparatorWithSpaces = separators.getObjectFieldValueSeparator() + " ";
+                return this;
+            }
+        };
+        pp.indentArraysWith(DefaultIndenter.SYSTEM_LINEFEED_INSTANCE);
+        return pp;
+    }
+
+    private static ObjectMapper buildObjectMapper() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);
+        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
+
+        objectMapper.setVisibility(objectMapper.getSerializationConfig().getDefaultVisibilityChecker()
+                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
+                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
+                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
+                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));
+        return objectMapper;
     }
 
     private static void validateExpectCall(Snapshot snapshot) {

src/test/java/io/github/jsonSnapshot/SnapshotIntegrationTest.java

@@ -65,6 +65,6 @@ public void shouldThrowStackOverflowError() {
         fakeObject1.setFakeObject(fakeObject2);
         fakeObject2.setFakeObject(fakeObject1);
 
-        assertThrows(StackOverflowError.class, () -> expect(fakeObject1).toMatchSnapshot());
+        assertThrows(SnapshotMatchException.class, () -> expect(fakeObject1).toMatchSnapshot());
     }
 }

src/test/java/io/github/jsonSnapshot/SnapshotTest.java

@@ -1,6 +1,5 @@
 package io.github.jsonSnapshot;
 
-import com.google.gson.GsonBuilder;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -34,8 +33,7 @@ public class SnapshotTest {
     public void setUp() throws NoSuchMethodException, IOException {
         snapshotFile = new SnapshotFile(DEFAULT_CONFIG.getFilePath(), "anyFilePath");
         snapshot = new Snapshot(snapshotFile, String.class,
-                String.class.getDeclaredMethod("toString"),
-                (object) -> new GsonBuilder().setPrettyPrinting().create().toJson(object),"anyObject");
+                String.class.getDeclaredMethod("toString"), SnapshotMatcher.defaultJsonFunction(),"anyObject");
     }
 
     @AfterEach