fix: validate multipleOf fails on float-point value (#295)

* fix: validate multipleOf fails on float-point value

* make clang-tidy happy.

* fix test case error when multipleOf is float but number is int

* fix multiple of float number

Author: dhmemi

.gitignore

@@ -4,3 +4,4 @@ cmake-build-*
 venv
 env
 compile_commands.json
+.vs/*

src/json-validator.cpp

@@ -864,7 +864,12 @@ class numeric : public schema
 	bool violates_multiple_of(T x) const
 	{
 		double res = std::remainder(x, multipleOf_.second);
+		double multiple = std::fabs(x / multipleOf_.second);
+		if (multiple > 1) {
+			res = res / multiple;
+		}
 		double eps = std::nextafter(x, 0) - static_cast<double>(x);
+
 		return std::fabs(res) > std::fabs(eps);
 	}
 

test/CMakeLists.txt

@@ -43,6 +43,10 @@ add_executable(issue-98 issue-98.cpp)
 target_link_libraries(issue-98 nlohmann_json_schema_validator)
 add_test(NAME issue-98-erase-exception-unknown-keywords COMMAND issue-98)
 
+add_executable(issue-293 issue-293.cpp)
+target_link_libraries(issue-293 nlohmann_json_schema_validator)
+add_test(NAME issue-293-float-point-error COMMAND issue-293)
+
 # 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-293.cpp

@@ -0,0 +1,32 @@
+#include "nlohmann/json-schema.hpp"
+
+using nlohmann::json_schema::json_validator;
+
+template <typename T>
+int should_throw(const nlohmann::json &schema, T value)
+{
+	try {
+		json_validator(schema).validate(value);
+	} catch (const std::exception &ex) {
+		return 0;
+	}
+	return 1;
+}
+
+int main(void)
+{
+
+	json_validator({{"type", "number"}, {"multipleOf", 0.001}}).validate(0.3 - 0.2);
+	json_validator({{"type", "number"}, {"multipleOf", 3.3}}).validate(8.0 - 1.4);
+	json_validator({{"type", "number"}, {"multipleOf", 1000.01}}).validate((1000.03 - 0.02) * 15.0);
+	json_validator({{"type", "number"}, {"multipleOf", 0.001}}).validate(0.030999999999999993);
+	json_validator({{"type", "number"}, {"multipleOf", 0.100000}}).validate(1.9);
+	json_validator({{"type", "number"}, {"multipleOf", 100000.1}}).validate(9000009);
+
+	int exc_count = 0;
+	exc_count += should_throw({{"type", "number"}, {"multipleOf", 0.001}}, 0.3 - 0.2005);
+	exc_count += should_throw({{"type", "number"}, {"multipleOf", 1000.02}}, (1000.03 - 0.02) * 15.0);
+	exc_count += should_throw({{"type", "number"}, {"multipleOf", 100000.11}}, 9000009);
+
+	return exc_count;
+}