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Reduce test compile times (spike)

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Two changes roughly halve the CPU time needed to build the unit tests
(clang 21: ~300 s -> ~150 s, GCC 16: ~750-820 s -> ~395-420 s, Debug):

- Move the C++14/17/20-dependent tests into separate
  unit-<name>-cpp<N>.cpp files. A test file is built for every standard
  whose JSON_HAS_CPP_<N> macro it mentions, so far whole large files were
  rebuilt for C++14/17/20 because of a few #ifdef sections. The main files
  are now built for C++11 only; the ci_test_*_cxx<N> jobs still build
  every file for every standard.

- Add the CMake option JSON_TestUnityBuild (ON by default, OFF with
  MinGW): compatible test files are compiled in batches as one
  translation unit so they share the template instantiations of the
  library. Each file keeps its own CTest test, which runs the batch
  executable filtered to that file's test cases. The binary-format tests
  form an explicit group; the rest is batched by JSON_TestUnityBatchSize.

Fix the name clashes that merging files exposed, document the rules for
test files in tests/README.md, and point CONTRIBUTING.md to it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann committed 2026-10-09 16:49:45 +02:00
1 parent d33068da73
commit 993e37e7ec
44 files changed
+3965 -2225
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tests/src/unit-comparison.cpp
+11 -305
View File
@@ -6,12 +6,11 @@
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
// cmake/test.cmake selects the C++ standard versions with which to build a
// unit test based on the presence of JSON_HAS_CPP_<VERSION> macros.
// When using macros that are only defined for particular versions of the standard
// (e.g., JSON_HAS_FILESYSTEM for C++17 and up), please mention the corresponding
// version macro in a comment close by, like this:
// JSON_HAS_CPP_<VERSION> (do not remove; see note at top of file)
// cmake/test.cmake builds a unit test with C++ standards beyond C++11 only if the
// source file mentions the corresponding version macro. To avoid rebuilding this
// large file for every standard, tests that depend on the standard version (e.g.,
// those using JSON_HAS_FILESYSTEM, JSON_HAS_RANGES, or JSON_HAS_THREE_WAY_COMPARISON)
// go into a separate file unit-comparison-cpp<NN>.cpp. This file stays C++11-only.
#include "doctest_compatibility.h"
@@ -28,37 +27,6 @@
#include <nlohmann/json.hpp>
using nlohmann::json;
#if JSON_HAS_THREE_WAY_COMPARISON
// this can be replaced with the doctest stl extension header in version 2.5
namespace doctest
{
template<> struct StringMaker<std::partial_ordering>
{
static String convert(const std::partial_ordering& order)
{
if (order == std::partial_ordering::less)
{
return "std::partial_ordering::less";
}
if (order == std::partial_ordering::equivalent)
{
return "std::partial_ordering::equivalent";
}
if (order == std::partial_ordering::greater)
{
return "std::partial_ordering::greater";
}
if (order == std::partial_ordering::unordered)
{
return "std::partial_ordering::unordered";
}
return "{?}";
}
};
} // namespace doctest
#endif
namespace
{
// helper function to check std::less<json::value_t>
@@ -75,16 +43,6 @@ TEST_CASE("lexicographical comparison operators")
constexpr auto f_ = false;
constexpr auto _t = true;
constexpr auto nan = std::numeric_limits<json::number_float_t>::quiet_NaN();
#if JSON_HAS_THREE_WAY_COMPARISON
constexpr auto lt = std::partial_ordering::less;
constexpr auto gt = std::partial_ordering::greater;
constexpr auto eq = std::partial_ordering::equivalent;
constexpr auto un = std::partial_ordering::unordered;
#endif
#if JSON_HAS_THREE_WAY_COMPARISON
INFO("using 3-way comparison");
#endif
#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
INFO("using legacy comparison");
@@ -135,62 +93,13 @@ TEST_CASE("lexicographical comparison operators")
CAPTURE(i)
CAPTURE(j)
// check precomputed values
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((j_types[i] < j_types[j]) == expected_lt[i][j]);
#else
#if !JSON_HAS_THREE_WAY_COMPARISON
CHECK(operator<(j_types[i], j_types[j]) == expected_lt[i][j]);
#endif
CHECK(f(j_types[i], j_types[j]) == expected_lt[i][j]);
}
}
}
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
SECTION("comparison: 3-way")
{
std::vector<std::vector<std::partial_ordering>> expected =
{
//0 1 2 3 4 5 6 7 8 9
{eq, lt, lt, lt, lt, lt, lt, lt, lt, un}, // 0
{gt, eq, lt, lt, lt, lt, lt, lt, lt, un}, // 1
{gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, // 2
{gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, // 3
{gt, gt, eq, eq, eq, lt, lt, lt, lt, un}, // 4
{gt, gt, gt, gt, gt, eq, lt, lt, lt, un}, // 5
{gt, gt, gt, gt, gt, gt, eq, lt, lt, un}, // 6
{gt, gt, gt, gt, gt, gt, gt, eq, lt, un}, // 7
{gt, gt, gt, gt, gt, gt, gt, gt, eq, un}, // 8
{un, un, un, un, un, un, un, un, un, un}, // 9
};
// check expected partial_ordering against expected boolean
REQUIRE(expected.size() == expected_lt.size());
for (size_t i = 0; i < expected.size(); ++i)
{
REQUIRE(expected[i].size() == expected_lt[i].size());
for (size_t j = 0; j < expected[i].size(); ++j)
{
CAPTURE(i)
CAPTURE(j)
CHECK(std::is_lt(expected[i][j]) == expected_lt[i][j]);
}
}
// check 3-way comparison against expected partial_ordering
REQUIRE(expected.size() == j_types.size());
for (size_t i = 0; i < j_types.size(); ++i)
{
REQUIRE(expected[i].size() == j_types.size());
for (size_t j = 0; j < j_types.size(); ++j)
{
CAPTURE(i)
CAPTURE(j)
CHECK((j_types[i] <=> j_types[j]) == expected[i][j]); // *NOPAD*
}
}
}
#endif
}
SECTION("values")
@@ -319,18 +228,6 @@ TEST_CASE("lexicographical comparison operators")
CHECK_FALSE(above_int64_max <= max_int64);
CHECK(above_int64_max > max_int64);
CHECK(above_int64_max >= max_int64);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((negative_one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
CHECK((negative_one <=> max_uint64) == std::partial_ordering::less); // *NOPAD*
CHECK((max_uint64 <=> negative_one) == std::partial_ordering::greater); // *NOPAD*
CHECK((one <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> one) == std::partial_ordering::greater); // *NOPAD*
CHECK((max_int64 <=> above_int64_max) == std::partial_ordering::less); // *NOPAD*
CHECK((above_int64_max <=> max_int64) == std::partial_ordering::greater); // *NOPAD*
#endif
}
SECTION("integer/float mixed comparison is exact")
@@ -381,16 +278,6 @@ TEST_CASE("lexicographical comparison operators")
CHECK_FALSE(json(1) < json(nan));
CHECK_FALSE(json(nan) < json(1));
CHECK_FALSE(json(1u) == json(nan));
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((max_int64 <=> two_63) == std::partial_ordering::less); // *NOPAD*
CHECK((two_63 <=> max_int64) == std::partial_ordering::greater); // *NOPAD*
CHECK((below_two_63 <=> max_int64) == std::partial_ordering::less); // *NOPAD*
CHECK((max_uint64 <=> two_64) == std::partial_ordering::less); // *NOPAD*
CHECK((json(1) <=> json(1.0)) == std::partial_ordering::equivalent); // *NOPAD*
CHECK((json(1) <=> json(nan)) == std::partial_ordering::unordered); // *NOPAD*
#endif
}
SECTION("compares unordered")
@@ -617,72 +504,6 @@ TEST_CASE("lexicographical comparison operators")
}
}
}
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
SECTION("comparison: 3-way")
{
std::vector<std::vector<std::partial_ordering>> expected =
{
//0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
{eq, eq, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, un, un}, // 0
{eq, eq, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, un, un}, // 1
{gt, gt, eq, lt, lt, lt, lt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 2
{gt, gt, gt, eq, gt, gt, gt, gt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 3
{gt, gt, gt, lt, eq, lt, gt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 4
{gt, gt, gt, lt, gt, eq, gt, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 5
{gt, gt, gt, lt, lt, lt, eq, lt, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 6
{gt, gt, gt, lt, gt, gt, gt, eq, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 7
{gt, gt, un, un, un, un, un, un, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 8
{gt, gt, un, un, un, un, un, un, un, un, lt, lt, gt, gt, lt, lt, lt, lt, lt, lt, un, un}, // 9
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, gt, gt, gt, gt, gt, gt, gt, lt, lt, un, un}, // 10
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, eq, gt, gt, gt, gt, gt, gt, lt, lt, un, un}, // 11
{gt, gt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, eq, gt, lt, lt, lt, lt, lt, lt, un, un}, // 12
{gt, gt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, lt, eq, lt, lt, lt, lt, lt, lt, un, un}, // 13
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, eq, lt, gt, gt, lt, lt, un, un}, // 14
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, gt, eq, gt, gt, lt, lt, un, un}, // 15
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, lt, lt, eq, gt, lt, lt, un, un}, // 16
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, lt, lt, gt, gt, lt, lt, lt, eq, lt, lt, un, un}, // 17
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, lt, un, un}, // 18
{gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, gt, eq, un, un}, // 19
{un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un}, // 20
{un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un, un}, // 21
};
// check expected partial_ordering against expected booleans
REQUIRE(expected.size() == expected_eq.size());
REQUIRE(expected.size() == expected_lt.size());
for (size_t i = 0; i < expected.size(); ++i)
{
REQUIRE(expected[i].size() == expected_eq[i].size());
REQUIRE(expected[i].size() == expected_lt[i].size());
for (size_t j = 0; j < expected[i].size(); ++j)
{
CAPTURE(i)
CAPTURE(j)
CHECK(std::is_eq(expected[i][j]) == expected_eq[i][j]);
CHECK(std::is_lt(expected[i][j]) == expected_lt[i][j]);
if (std::is_gt(expected[i][j]))
{
CHECK((!expected_eq[i][j] && !expected_lt[i][j]));
}
}
}
// check that two values compare according to their expected ordering
REQUIRE(expected.size() == j_values.size());
for (size_t i = 0; i < j_values.size(); ++i)
{
REQUIRE(expected[i].size() == j_values.size());
for (size_t j = 0; j < j_values.size(); ++j)
{
CAPTURE(i)
CAPTURE(j)
CHECK((j_values[i] <=> j_values[j]) == expected[i][j]); // *NOPAD*
}
}
}
#endif
}
#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
@@ -721,60 +542,7 @@ TEST_CASE("lexicographical comparison operators")
#endif
}
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
TEST_CASE("regression #3868 - heterogeneous comparisons compile under C++20 (P2468R2)")
{
// Issue #3868: operator!= was preventing compiler from synthesizing reversed
// operator== candidates under C++20's P2468R2 rewritten candidate rules.
// Verify that heterogeneous comparisons now work.
SECTION("string vs json")
{
std::string s = "string";
json j = "string";
CHECK(s == j);
CHECK(j == s);
CHECK_FALSE(s != j);
CHECK_FALSE(j != s);
}
SECTION("other heterogeneous types")
{
int i = 42;
json j = 42;
CHECK(i == j);
CHECK(j == i);
CHECK_FALSE(i != j);
CHECK_FALSE(j != i);
}
}
#if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
TEST_CASE("regression #5665 - scalar <= discarded and scalar >= discarded in C++20 legacy mode")
{
// Issue #5665: with a scalar on the left-hand side, <= and >= only had the
// candidate rewritten from operator<=>, which does not emulate the legacy
// discarded-value behavior. Check that scalar-on-the-left now matches the
// other three operand orders.
const json discarded(json::value_t::discarded);
const json one = 1;
CHECK(discarded <= 1);
CHECK(discarded >= 1);
CHECK(one <= discarded);
CHECK(one >= discarded);
CHECK(1 <= discarded);
CHECK(1 >= discarded);
CHECK(1.5 <= discarded);
CHECK(1.5 >= discarded);
}
#endif
#endif
namespace
namespace unit_comparison_detail
{
// orders keys ascending or descending, as chosen when a map is created
template<class Key>
@@ -906,7 +674,9 @@ struct case_insensitive_less
template<class Key, class Value, class /*Compare*/, class Allocator>
using case_insensitive_map = std::map<Key, Value, case_insensitive_less, Allocator>;
using ci_json = nlohmann::json::with_object_t<case_insensitive_map>;
} // namespace
} // namespace unit_comparison_detail
using namespace unit_comparison_detail; // NOLINT(google-build-using-namespace)
TEST_CASE("equality of objects whose entries have no fixed order")
{
@@ -1049,12 +819,6 @@ TEST_CASE("containers are compared element by element")
CHECK(a < b);
CHECK(b > a);
CHECK_FALSE(b < a);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((a <=> b) == std::partial_ordering::less); // *NOPAD*
CHECK((b <=> a) == std::partial_ordering::greater); // *NOPAD*
CHECK((a <=> a) == std::partial_ordering::equivalent); // *NOPAD*
#endif
}
// a container that is a prefix of the other one
@@ -1072,11 +836,6 @@ TEST_CASE("containers are compared element by element")
CHECK(smaller_object < larger_object);
CHECK(larger_object > smaller_object);
CHECK_FALSE(smaller_object == larger_object);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
CHECK((shorter <=> longer) == std::partial_ordering::less); // *NOPAD*
CHECK((longer <=> shorter) == std::partial_ordering::greater); // *NOPAD*
#endif
}
// elements that cannot be ordered
@@ -1087,13 +846,7 @@ TEST_CASE("containers are compared element by element")
CHECK_FALSE(lhs == lhs);
CHECK_FALSE(rhs < lhs);
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
// operator<=> stops there, as std::lexicographical_compare_three_way
// does, and operator< is derived from it
CHECK((lhs <=> rhs) == std::partial_ordering::unordered); // *NOPAD*
CHECK_FALSE(lhs < rhs);
#else
#if !JSON_HAS_THREE_WAY_COMPARISON
// operator< skips a pair of elements that cannot be ordered, as
// std::lexicographical_compare does, and the next pair decides
CHECK(lhs < rhs);
@@ -1102,50 +855,3 @@ TEST_CASE("containers are compared element by element")
}
}
#if JSON_HAS_THREE_WAY_COMPARISON
// JSON_HAS_CPP_20 (do not remove; see note at top of file)
TEST_CASE("operator<=> of binary values with a different subtype does not depend on nesting depth")
{
// #5654: std::vector<std::uint8_t>::operator<=>, which the binary type's
// own operator<=> uses, ignores the subtype that operator== checks. So a
// pair of binary values with the same bytes but a different subtype is
// unequal, yet <=>-equivalent - the same inconsistency between == and <=>
// that a NaN has. Within the nesting bound, an array compares itself
// with std::vector's own operator<=>, which treats an equivalent pair as
// undecided and lets the next element decide, same as
// std::lexicographical_compare_three_way does. Past the bound,
// compare_iteratively<true>() takes over and must classify the pair the
// same way, or the result of operator<=> - and of <, which C++20 derives
// from it - depends on how deeply the values are nested.
const json a = json::array({json::binary({1}, 1), 1});
const json b = json::array({json::binary({1}, 2), 2});
// the root inconsistency: unequal, yet <=>-equivalent
CHECK_FALSE(a[0] == b[0]);
CHECK((a[0] <=> b[0]) == std::partial_ordering::equivalent); // *NOPAD*
const auto deep = [](const json & j, const std::size_t depth)
{
json result = j;
for (std::size_t i = 0; i < depth; ++i)
{
result = json::array({std::move(result)});
}
return result;
};
// 127 levels stay within nesting_depth_limit() (128); 128 and 200 do not,
// and must still agree with the levels that do
for (const std::size_t depth : std::vector<std::size_t> {0, 127, 128, 200})
{
CAPTURE(depth)
const json x = deep(a, depth);
const json y = deep(b, depth);
CHECK((x <=> y) == std::partial_ordering::less); // *NOPAD*
CHECK((y <=> x) == std::partial_ordering::greater); // *NOPAD*
CHECK(x < y);
CHECK(y > x);
CHECK_FALSE(y < x);
}
}
#endif