test(data): add test on json to xml data conversion

For a weird case in pairwise data.

pom.xml

@@ -99,7 +99,7 @@
 
 		<dependency>
 			<groupId>org.xmlunit</groupId>
-			<artifactId>xmlunit-matchers</artifactId>
+			<artifactId>xmlunit-assertj3</artifactId>
 			<version>2.10.0</version>
 			<scope>test</scope>
 		</dependency>

src/test/java/fr/insee/lunatic/conversion/data/JsonToXmlDataTest.java

@@ -0,0 +1,58 @@
+package fr.insee.lunatic.conversion.data;
+
+import org.junit.jupiter.api.Test;
+import org.xmlunit.assertj3.XmlAssert;
+
+class JsonToXmlDataTest {
+
+    /**
+     * Lunatic bug: in some cases pairwise data can be inconsistent.
+     * Yet the data conversion shouldn't fail so as not to break the data extraction of client collection tools
+     * that uses the json to xml conversion.
+     */
+    @Test
+    void convertInconsistentPairwiseData() throws Exception {
+        // Given
+        String jsonInconsistentData = """
+                {
+                  "COLLECTED": {
+                    "LIENS_MISSING": {
+                      "COLLECTED": [
+                        null,
+                        [null, null]
+                      ]
+                    }
+                  },
+                  "CALCULATED": {},
+                  "EXTERNAL": {
+                    "FOO_EXTERNAL": "some value"
+                  }
+                }""";
+        // When
+        JSONLunaticDataToXML converter = new JSONLunaticDataToXML();
+        String result = converter.transform(jsonInconsistentData);
+        // Then
+        String expected = """
+                <?xml version="1.0" encoding="UTF-8"?>
+                <Data>
+                  <COLLECTED>
+                    <LIENS_MISSING>
+                      <COLLECTED>
+                        <COLLECTED type="null"/>
+                        <COLLECTED>
+                          <COLLECTED type="null"/>
+                          <COLLECTED type="null"/>
+                        </COLLECTED>
+                      </COLLECTED>
+                    </LIENS_MISSING>
+                  </COLLECTED>
+                  <CALCULATED/>
+                  <EXTERNAL>
+                    <FOO_EXTERNAL type="string">some value</FOO_EXTERNAL>
+                  </EXTERNAL>
+                </Data>
+                """;
+        XmlAssert.assertThat(expected).and(result).ignoreWhitespace().areIdentical();
+    }
+
+}