Add simple unit test for optional values

test/CMakeLists.txt

@@ -35,6 +35,10 @@ add_executable(issue-70-root-schema-constructor issue-70-root-schema-constructor
 target_link_libraries(issue-70-root-schema-constructor nlohmann_json_schema_validator)
 add_test(NAME issue-70-root-schema-constructor COMMAND issue-70-root-schema-constructor)
 
+add_executable(issue-25-default-values issue-25-default-values.cpp)
+target_link_libraries(issue-25-default-values nlohmann_json_schema_validator)
+add_test(NAME issue-25-default-values COMMAND issue-25-default-values)
+
 # Unit test for string format checks
 add_executable("string-format-check-test" "string-format-check-test.cpp")
 target_include_directories("string-format-check-test" PRIVATE "${PROJECT_SOURCE_DIR}/src/")

test/issue-25-default-values.cpp

@@ -0,0 +1,100 @@
+#include <iostream>
+#include <nlohmann/json-schema.hpp>
+
+using nlohmann::json;
+using nlohmann::json_schema::json_validator;
+
+static const json person_schema = R"(
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "A person",
+    "properties": {
+        "name": {
+            "description": "Name",
+            "type": "string"
+        },
+        "age": {
+            "description": "Age of the person",
+            "type": "number",
+            "minimum": 2,
+            "maximum": 200
+        },
+            "address":{
+                "type": "object",
+                "properties":{
+                    "street":{
+                        "type": "string",
+                        "default": "Abbey Road"
+            }
+          }
+        }
+    },
+    "required": [
+                 "name",
+                 "age"
+                 ],
+    "additionalProperties": false,
+    "type": "object"
+})"_json;
+
+int main(void)
+{
+	json_validator validator{};
+
+	// add address which is optional that should generate a diff containing a default street
+	json person_missing_address = R"({
+    "name": "Hans",
+    "age": 69,
+    "address": {}
+})"_json;
+
+	validator.set_root_schema(person_schema);
+
+	const auto default_patch = validator.validate(person_missing_address);
+
+	if (!default_patch.is_array()) {
+		std::cerr << "Patch with defaults is expected to be an array" << std::endl;
+		return 1;
+	}
+
+	if (default_patch.size() != 1) {
+		std::cerr << "Patch with defaults is expected to contain one opperation" << std::endl;
+		return 1;
+	}
+
+	const auto &single_op = default_patch[0];
+
+	if (!single_op.contains("op")) {
+		std::cerr << "Patch with defaults is expected to contain opperation entry" << std::endl;
+		return 1;
+	}
+
+	if (single_op["op"].get<std::string>() != "add") {
+		std::cerr << "Patch with defaults is expected to contain add opperation" << std::endl;
+		return 1;
+	}
+
+	if (!single_op.contains("path")) {
+		std::cerr << "Patch with defaults is expected to contain a path" << std::endl;
+		return 1;
+	}
+
+	const auto &readPath = single_op["path"].get<std::string>();
+	if (readPath != "/address/street") {
+		std::cerr << "Patch with defaults contains wrong path. It is " << readPath << " and should be "
+		          << "/address/street" << std::endl;
+		return 1;
+	}
+
+	if (!single_op.contains("value")) {
+		std::cerr << "Patch with defaults is expected to contain a value" << std::endl;
+		return 1;
+	}
+
+	if (single_op["value"].get<std::string>() != "Abbey Road") {
+		std::cerr << "Patch with defaults contains wrong value" << std::endl;
+		return 1;
+	}
+
+	return 0;
+}