feat: allow to have equality between null and empty array

src/main/java/com/deblock/jsondiff/matcher/CompositeJsonMatcher.java

@@ -6,32 +6,24 @@
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.fasterxml.jackson.databind.node.ValueNode;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
 public class CompositeJsonMatcher implements JsonMatcher {
-    private final PartialJsonMatcher<ArrayNode> jsonArrayPartialMatcher;
-    private final PartialJsonMatcher<ObjectNode> jsonObjectPartialMatcher;
-    private final PartialJsonMatcher<ValueNode> primitivePartialMatcher;
+    private final List<PartialJsonMatcher<JsonNode>> matchers;
 
-    public CompositeJsonMatcher(
-        PartialJsonMatcher<ArrayNode> jsonArrayPartialMatcher,
-        PartialJsonMatcher<ObjectNode> jsonObjectPartialMatcher,
-        PartialJsonMatcher<ValueNode> primitivePartialMatcher
-    ) {
-        this.jsonArrayPartialMatcher = jsonArrayPartialMatcher;
-        this.jsonObjectPartialMatcher = jsonObjectPartialMatcher;
-        this.primitivePartialMatcher = primitivePartialMatcher;
+    public CompositeJsonMatcher(PartialJsonMatcher<?> ...jsonArrayPartialMatcher) {
+        this.matchers = new ArrayList<>();
+        Arrays.stream(jsonArrayPartialMatcher).forEach(it -> this.matchers.add((PartialJsonMatcher<JsonNode>) it));
     }
 
     @Override
     public JsonDiff diff(Path path, JsonNode expected, JsonNode received) {
-        if (expected instanceof ObjectNode  && received instanceof ObjectNode) {
-            return this.jsonObjectPartialMatcher.jsonDiff(path, (ObjectNode) expected, (ObjectNode) received, this);
-        } else if (expected instanceof ArrayNode && received instanceof ArrayNode) {
-            return this.jsonArrayPartialMatcher.jsonDiff(path, (ArrayNode) expected, (ArrayNode) received, this);
-        } else if (expected instanceof ValueNode && received instanceof ValueNode){
-            return this.primitivePartialMatcher.jsonDiff(path, (ValueNode) expected, (ValueNode) received, this);
-        } else {
-            return new UnMatchedPrimaryDiff(path, expected, received);
-        }
+        return this.matchers.stream()
+                .filter(matcher -> matcher.manage(expected, received))
+                .findFirst()
+                .map(matcher -> matcher.jsonDiff(path, expected, received, this))
+                .orElseGet(() -> new UnMatchedPrimaryDiff(path, expected, received));
     }
-
 }

src/main/java/com/deblock/jsondiff/matcher/JsonMatcher.java

@@ -6,5 +6,4 @@
 public interface JsonMatcher {
 
     JsonDiff diff(Path path, JsonNode expected, JsonNode received);
-
 }

src/main/java/com/deblock/jsondiff/matcher/LenientJsonArrayPartialMatcher.java

@@ -2,6 +2,7 @@
 
 import com.deblock.jsondiff.diff.JsonArrayDiff;
 import com.deblock.jsondiff.diff.JsonDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ArrayNode;
 
 import java.util.*;
@@ -51,6 +52,11 @@ public JsonDiff jsonDiff(Path path, ArrayNode expectedValues, ArrayNode received
         return diff;
     }
 
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isArray() && received.isArray();
+    }
+
     private double maxSimilarityRate(Map.Entry<Integer, Map<Integer, JsonDiff>> entry) {
         return entry.getValue().values().stream().mapToDouble(JsonDiff::similarityRate).max().orElse(0);
     }

src/main/java/com/deblock/jsondiff/matcher/LenientJsonObjectPartialMatcher.java

@@ -2,6 +2,7 @@
 
 import com.deblock.jsondiff.diff.JsonDiff;
 import com.deblock.jsondiff.diff.JsonObjectDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 
 public class LenientJsonObjectPartialMatcher implements PartialJsonMatcher<ObjectNode> {
@@ -26,4 +27,9 @@ public JsonDiff jsonDiff(Path path, ObjectNode expectedJson, ObjectNode received
 
         return jsonDiff;
     }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isObject() && received.isObject();
+    }
 }

src/main/java/com/deblock/jsondiff/matcher/LenientNumberPrimitivePartialMatcher.java

@@ -3,6 +3,7 @@
 import com.deblock.jsondiff.diff.JsonDiff;
 import com.deblock.jsondiff.diff.MatchedPrimaryDiff;
 import com.deblock.jsondiff.diff.UnMatchedPrimaryDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.NumericNode;
 import com.fasterxml.jackson.databind.node.ValueNode;
 
@@ -30,4 +31,9 @@ public JsonDiff jsonDiff(Path path, ValueNode expectedValue, ValueNode receivedV
 
         return delegated.jsonDiff(path, expectedValue, receivedValue, jsonMatcher);
     }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isValueNode() && received.isValueNode();
+    }
 }

src/main/java/com/deblock/jsondiff/matcher/NullEqualsEmptyArrayMatcher.java

@@ -0,0 +1,26 @@
+package com.deblock.jsondiff.matcher;
+
+import com.deblock.jsondiff.diff.JsonDiff;
+import com.deblock.jsondiff.diff.MatchedPrimaryDiff;
+import com.deblock.jsondiff.diff.UnMatchedPrimaryDiff;
+import com.fasterxml.jackson.databind.JsonNode;
+
+public class NullEqualsEmptyArrayMatcher implements PartialJsonMatcher<JsonNode> {
+
+    @Override
+    public JsonDiff jsonDiff(Path path, JsonNode expectedJson, JsonNode receivedJson, JsonMatcher jsonMatcher) {
+        if (
+                (expectedJson.isNull() && receivedJson.isEmpty())
+                || (receivedJson.isNull() && expectedJson.isEmpty())
+        ) {
+            return new MatchedPrimaryDiff(path, expectedJson);
+        }
+        return new UnMatchedPrimaryDiff(path, expectedJson, receivedJson);
+    }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return (expected.isNull() && received.isArray())
+                 || (received.isNull() && expected.isArray());
+    }
+}

src/main/java/com/deblock/jsondiff/matcher/PartialJsonMatcher.java

@@ -5,4 +5,7 @@
 
 public interface PartialJsonMatcher<T extends JsonNode> {
     JsonDiff jsonDiff(Path path, T expectedJson, T receivedJson, JsonMatcher jsonMatcher);
+
+    boolean manage(JsonNode expected, JsonNode received);
+
 }

src/main/java/com/deblock/jsondiff/matcher/StrictJsonArrayPartialMatcher.java

@@ -2,6 +2,7 @@
 
 import com.deblock.jsondiff.diff.JsonArrayDiff;
 import com.deblock.jsondiff.diff.JsonDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ArrayNode;
 
 import java.util.Comparator;
@@ -35,4 +36,9 @@ public JsonDiff jsonDiff(Path path, ArrayNode expectedValues, ArrayNode received
         }
         return diff;
     }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isArray() && received.isArray();
+    }
 }

src/main/java/com/deblock/jsondiff/matcher/StrictJsonObjectPartialMatcher.java

@@ -2,6 +2,7 @@
 
 import com.deblock.jsondiff.diff.JsonDiff;
 import com.deblock.jsondiff.diff.JsonObjectDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 
 import java.util.stream.Collectors;
@@ -43,4 +44,9 @@ public JsonDiff jsonDiff(Path path, ObjectNode expectedJson, ObjectNode received
 
         return jsonDiff;
     }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isObject() && received.isObject();
+    }
 }

src/main/java/com/deblock/jsondiff/matcher/StrictPrimitivePartialMatcher.java

@@ -3,6 +3,7 @@
 import com.deblock.jsondiff.diff.JsonDiff;
 import com.deblock.jsondiff.diff.MatchedPrimaryDiff;
 import com.deblock.jsondiff.diff.UnMatchedPrimaryDiff;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ValueNode;
 
 import java.util.Objects;
@@ -17,4 +18,9 @@ public JsonDiff jsonDiff(Path path, ValueNode expectedValue, ValueNode receivedV
             return new UnMatchedPrimaryDiff(path, expectedValue, receivedValue);
         }
     }
+
+    @Override
+    public boolean manage(JsonNode expected, JsonNode received) {
+        return expected.isValueNode() && received.isValueNode();
+    }
 }

src/test/java/com/deblock/jsondiff/Sample.java

@@ -6,12 +6,13 @@
 
 public class Sample {
     public static void main(String[] args) {
-        final var expectedJson = "{\"array\": [{\"b\": [1]}, {\"a\": [1, 5]}]}";
-        final var receivedJson = "{\"array\": [{\"a\": [1]}]}";
+        final var expectedJson = "{\"array\": []}";
+        final var receivedJson = "{}";
 
         // define your matcher
         // CompositeJsonMatcher use other matcher to perform matching on objects, list or primitive
         final var jsonMatcher = new CompositeJsonMatcher(
+            new NullEqualsEmptyArrayMatcher(),
             new LenientJsonArrayPartialMatcher(), // comparing array using lenient mode (ignore array order and extra items)
             new LenientJsonObjectPartialMatcher(), // comparing object using lenient mode (ignoring extra properties)
             new LenientNumberPrimitivePartialMatcher(new StrictPrimitivePartialMatcher()) // comparing primitive types and manage numbers (100.00 == 100)