results: fix Debug rendering assertion

Check the character in the output string instead of referring to a nonexistent grid_ member. This restores Debug compilation while preserving the intended invariant that rendering must not write an identical character twice.

Size labels intentionally replace interior spaces, so requiring an entirely unwritten destination would reject valid solutions. Update the testing notes now that Debug builds pass.

Tests: Debug and Release CTest suites (4 passed each)

Refs: #7

CMakeLists.txt

@@ -13,5 +13,6 @@ if(BUILD_TESTING)
           tests/tests.cc)
   add_test(NAME validator COMMAND partridge_tests validator)
   add_test(NAME construction COMMAND partridge_tests construction)
+  add_test(NAME rendering COMMAND partridge_tests rendering)
   add_test(NAME solver-small COMMAND partridge_tests solver-small)
 endif()

TESTING.md

@@ -12,7 +12,8 @@ ctest --test-dir build --output-on-failure
 The tests independently check board dimensions, square multiplicities, bounds,
 overlap, and complete coverage.  They cover small unsatisfiable solver inputs, a
 known order-8 solution, invalid placement diagnostics, and construction of an
-order-9 solution from the order-8 fixture.
+order-9 solution from the order-8 fixture.  The rendering test also formats the
+known order-8 solution and checks the resulting grid dimensions and coverage.
 
 ## Debug and sanitizers
 
@@ -37,6 +38,6 @@ ctest --test-dir build-ubsan --output-on-failure
 ```
 
 The sanitizer flags shown are supported by Clang and GCC.  Other compilers may
-require different flags.  Debug compilation and a feasible solver run currently
-expose the pre-existing defects tracked by issues #7 and #14 respectively; the
-test additions deliberately do not include fixes for those separate issues.
+require different flags.  A feasible solver run currently exposes the
+pre-existing defect tracked by issue #14; the test additions deliberately do
+not include its separate fix.

main.cc

@@ -85,7 +85,8 @@ namespace {
     auto set(std::string &s, size_t x, size_t y, char c) const noexcept -> void {
       assert(x < length_);
       assert(y < length_);
-      assert(grid_[x + y * length_] != c);
+      // Size labels may replace interior spaces, but must not duplicate a write.
+      assert(s[x + y * length_] != c);
       s[x + y * length_] = c;
     }
 

tests/tests.cc

@@ -138,6 +138,16 @@ namespace {
     };
   }
 
+  auto renderable_result(std::uint64_t side,
+                         std::vector<Placement> const &placements) -> Results {
+    std::vector<Square> squares;
+    squares.reserve(placements.size());
+    for (auto const &placement: placements) {
+      squares.emplace_back(placement.x + placement.y * side, placement.side);
+    }
+    return Results(side, std::move(squares));
+  }
+
   auto construct_next_odd(std::uint64_t even_order,
                           std::vector<Placement> placements)
       -> std::vector<Placement> {
@@ -221,6 +231,29 @@ namespace {
                   "even-to-odd construction was rejected:\n" + validation.text());
   }
 
+  auto test_rendering() -> int {
+    auto const result = renderable_result(36, known_order_8());
+    std::ostringstream rendered;
+    auto *const original_buffer = std::cout.rdbuf(rendered.rdbuf());
+    result.output();
+    std::cout.rdbuf(original_buffer);
+
+    int failures = 0;
+    std::istringstream lines(rendered.str());
+    std::string line;
+    std::uint64_t line_count = 0;
+    while (std::getline(lines, line)) {
+      ++line_count;
+      failures += expect(line.size() == result.length(),
+                         "rendered row has incorrect width");
+      failures += expect(line.find('.') == std::string::npos,
+                         "valid solution left an unrendered cell");
+    }
+    failures += expect(line_count == result.length(),
+                       "rendered output has incorrect height");
+    return failures;
+  }
+
   auto test_small_solver() -> int {
     int failures = 0;
     for (auto const order: std::array<std::uint64_t, 2>{2, 3}) {
@@ -262,6 +295,9 @@ int main(int argc, char **argv) {
   if (test == "construction") {
     return test_construction();
   }
+  if (test == "rendering") {
+    return test_rendering();
+  }
   if (test == "solver-small") {
     return test_small_solver();
   }