feat: add invariant-based test suite (50+ uncheateable tests)

CMakeLists.txt

@@ -116,16 +116,16 @@ option(BUILD_TESTS "Build test suite" ON)
 if(BUILD_TESTS)
     enable_testing()
 
-
-    add_executable(test_framebuffer tests/test_framebuffer.cpp)
-    target_link_libraries(test_framebuffer PRIVATE soft_render)
-    add_test(NAME test_framebuffer COMMAND test_framebuffer)
-
-    add_executable(test_vec3 tests/test_vec3.cpp)
-    target_link_libraries(test_vec3 PRIVATE soft_render)
-    add_test(NAME test_vec3 COMMAND test_vec3)
-
-    add_executable(tests tests/test_math.cpp)
-    target_link_libraries(tests PRIVATE soft_render)
-    add_test(NAME test_math COMMAND tests)
+    function(sr_add_test name source)
+        add_executable(${name} ${source})
+        target_link_libraries(${name} PRIVATE soft_render)
+        add_test(NAME ${name} COMMAND ${name})
+    endfunction()
+
+    sr_add_test(test_framebuffer       tests/test_framebuffer.cpp)
+    sr_add_test(test_vec3              tests/test_vec3.cpp)
+    sr_add_test(tests                  tests/test_math.cpp)
+    sr_add_test(test_math_invariants   tests/test_math_invariants.cpp)
+    sr_add_test(test_rasterizer        tests/test_rasterizer.cpp)
+    sr_add_test(test_pipeline_integration tests/test_pipeline_integration.cpp)
 endif()

tests/test_helpers.hpp

@@ -0,0 +1,84 @@
+#pragma once
+
+// =============================================================================
+// test_helpers.hpp — Shared test utilities and tolerance constants
+//
+// All floating-point comparisons use these two tiers:
+//   EPS       (1e-4) — tight: single-operation results, exact math identities
+//   EPS_LOOSE (1e-2) — loose: chained transforms, accumulated floating-point error
+// =============================================================================
+
+#include <cmath>
+#include <cstdint>
+#include "soft_render/math/vec3.hpp"
+#include "soft_render/core/framebuffer.hpp"
+
+namespace sr_test {
+
+using sr::math::Vec3;
+using sr::core::Framebuffer;
+using sr::core::Pixel;
+
+// ---------------------------------------------------------------------------
+// Tolerance constants
+// ---------------------------------------------------------------------------
+constexpr float EPS       = 1e-4f;   // Single-operation precision
+constexpr float EPS_LOOSE = 1e-2f;   // Multi-operation / chained transforms
+constexpr float PI        = 3.14159265358979f;
+
+// ---------------------------------------------------------------------------
+// Floating-point comparison helpers
+// ---------------------------------------------------------------------------
+inline bool approx(float a, float b, float eps = EPS) {
+    return std::abs(a - b) < eps;
+}
+
+inline bool approxVec3(const Vec3& a, const Vec3& b, float eps = EPS) {
+    return approx(a.x, b.x, eps) && approx(a.y, b.y, eps) && approx(a.z, b.z, eps);
+}
+
+// ---------------------------------------------------------------------------
+// Deterministic PRNG (xorshift32) — reproducible but not hardcodeable
+// ---------------------------------------------------------------------------
+inline uint32_t& rng_state() {
+    static uint32_t s = 0xDEADBEEF;
+    return s;
+}
+
+inline float randf() {
+    auto& s = rng_state();
+    s ^= s << 13;
+    s ^= s >> 17;
+    s ^= s << 5;
+    return (s & 0xFFFFFF) / float(0xFFFFFF);
+}
+
+inline float randf_range(float lo, float hi) { return lo + randf() * (hi - lo); }
+
+inline Vec3 randVec3(float range = 10.f) {
+    return { randf_range(-range, range), randf_range(-range, range), randf_range(-range, range) };
+}
+
+inline Vec3 randUnitVec3() { return randVec3().normalized(); }
+
+// ---------------------------------------------------------------------------
+// Framebuffer inspection helpers
+// ---------------------------------------------------------------------------
+inline int countNonBlack(const Framebuffer& fb) {
+    int count = 0;
+    const Pixel* px = fb.pixels();
+    for (int i = 0; i < fb.width() * fb.height(); ++i)
+        if (px[i].r > 0 || px[i].g > 0 || px[i].b > 0) ++count;
+    return count;
+}
+
+inline Pixel getPixel(const Framebuffer& fb, int x, int y) {
+    return fb.pixels()[y * fb.width() + x];
+}
+
+inline bool isLit(const Framebuffer& fb, int x, int y) {
+    Pixel p = getPixel(fb, x, y);
+    return p.r > 0 || p.g > 0 || p.b > 0;
+}
+
+} // namespace sr_test