From c05e36b178450f0ecae9c53aa76e031cf3322d5c Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Fri, 11 Sep 2026 20:20:13 +0200
Subject: [PATCH] test: cover mustParse and BadDocument

---
 tests/testJson.cpp | 145 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 tests/testJson.cpp

diff --git a/tests/testJson.cpp b/tests/testJson.cpp
new file mode 100644
index 0000000..f61f9fe
--- /dev/null
+++ b/tests/testJson.cpp
@@ -0,0 +1,145 @@
+#include "testHarness.h"
+#include "vf/Json.h"
+
+#include <cstdio>
+#include <string>
+#include <vector>
+
+using namespace vf;
+
+namespace {
+
+const std::vector<std::string>& uglyDocuments() {
+    static const std::vector<std::string> documents = {
+        "{}",
+        "[]",
+        "null",
+        "true",
+        "false",
+        "0",
+        "-0",
+        "-17",
+        "3.5",
+        "1e-3",
+        "-2.5E+4",
+        "1e308",
+        "0.1",
+        "9223372036854775807",
+        "-9223372036854775808",
+        "\"\"",
+        "\"tab\\tnewline\\nquote\\\"backslash\\\\slash\\/bell\\bform\\fcarriage\\r\"",
+        "\"\\u0000 embedded nul, \\u001f control, \\u007f delete\"",
+        "\"\\u00e9\\u0141\\u4e2d\\ud83e\\udd8a\"",
+        "[[[[[[[[[[1]]]]]]]]]]",
+        "[1,2,3,[4,[5,[6]]],{\"deep\":{\"deeper\":{\"deepest\":[]}}}]",
+        "{\"\":\"empty key\"}",
+        "{\"a/b\":1,\"c~d\":2,\"e f\":3}",
+        "{\"duplicate\":1,\"duplicate\":2}",
+        "   \n\t  {\n \"spread\" :\t[ 1 ,\n 2 ]\n}  \n",
+        "{\"mixed\":[null,true,false,0,-0.0,\"\",{},[]]}",
+        "[{\"item\":\"voxelforge:iron_ingot\",\"count\":3,\"chance\":0.25}]",
+        "{\"nested\":{\"list\":[{\"a\":[{\"b\":[[[1]]]}]}]}}",
+        "{\"unicodeKey\\u00e9\":\"value\\u00e9\"}",
+    };
+    return documents;
+}
+
+JsonValue mustParse(const std::string& text) {
+    JsonParseResult parsed = parseJson(text);
+    CHECK(parsed.ok);
+    if (!parsed.ok) std::printf("  parse failed: %s\n", parsed.error.text().c_str());
+    return parsed.root;
+}
+
+std::string repeated(const std::string& unit, int times) {
+    std::string out;
+    out.reserve(unit.size() * static_cast<std::size_t>(times));
+    for (int i = 0; i < times; ++i) out += unit;
+    return out;
+}
+
+struct BadDocument {
+    const char* text;
+    int line;
+    int column;
+    const char* fragment;
+};
+
+} // namespace
+
+VF_TEST(everyUglyDocumentSurvivesParseWriteParseUnchanged) {
+    for (const std::string& text : uglyDocuments()) {
+        JsonParseResult first = parseJson(text);
+        CHECK(first.ok);
+        if (!first.ok) {
+            std::printf("  rejected: %s -> %s\n", text.c_str(), first.error.text().c_str());
+            continue;
+        }
+        std::string compact = JsonWriter::compact(first.root);
+        JsonParseResult second = parseJson(compact);
+        CHECK(second.ok);
+        CHECK(second.root == first.root);
+
+        std::string indented = JsonWriter::indented(first.root, 2);
+        JsonParseResult third = parseJson(indented);
+        CHECK(third.ok);
+        CHECK(third.root == first.root);
+
+        // The compact form is a fixed point: writing it again changes nothing.
+        CHECK_EQ(JsonWriter::compact(second.root), compact);
+        CHECK_EQ(JsonWriter::compact(third.root), compact);
+    }
+}
+
+VF_TEST(writtenDocumentsStayPureAsciiWhateverWentIn) {
+    JsonValue root = mustParse("{\"key\":\"\\u00e9\\u4e2d\\ud83e\\udd8a\"}");
+    std::string compact = JsonWriter::compact(root);
+    for (char c : compact) CHECK(static_cast<unsigned char>(c) < 0x80u);
+    CHECK_EQ(compact, std::string("{\"key\":\"\\u00e9\\u4e2d\\ud83e\\udd8a\"}"));
+
+    JsonWriter raw;
+    raw.escapeNonAscii = false;
+    std::string utf8 = raw.write(root);
+    CHECK(utf8.size() < compact.size());
+    bool carriesHighBytes = false;
+    for (char c : utf8)
+        if (static_cast<unsigned char>(c) >= 0x80u) carriesHighBytes = true;
+    CHECK(carriesHighBytes);
+    CHECK(parseJson(utf8).ok);
+    CHECK(parseJson(utf8).root == root);
+}
+
+VF_TEST(surrogatePairsBecomeOneCodePointAndComeBackOutAsAPair) {
+    JsonValue root = mustParse("[\"\\ud83e\\udd8a\"]");
+    const JsonValue* text = root.at(0u);
+    CHECK(text != nullptr);
+    CHECK_EQ(text->stringValue().size(), static_cast<std::size_t>(4));
+    CHECK_EQ(static_cast<unsigned char>(text->stringValue()[0]), 0xF0u);
+    CHECK_EQ(static_cast<unsigned char>(text->stringValue()[1]), 0x9Fu);
+    CHECK_EQ(static_cast<unsigned char>(text->stringValue()[2]), 0xA6u);
+    CHECK_EQ(static_cast<unsigned char>(text->stringValue()[3]), 0x8Au);
+    CHECK_EQ(JsonWriter::compact(root), std::string("[\"\\ud83e\\udd8a\"]"));
+
+    JsonValue latin = mustParse("\"\\u00e9\"");
+    CHECK_EQ(latin.stringValue().size(), static_cast<std::size_t>(2));
+    CHECK_EQ(JsonWriter::compact(latin), std::string("\"\\u00e9\""));
+}
+
+VF_TEST(brokenSurrogatesAndUnknownEscapesAreRefused) {
+    const char* broken[] = {
+        "\"\\ud83e\"",          // high surrogate with nothing after it
+        "\"\\ud83eX\"",         // high surrogate followed by a plain character
+        "\"\\ud83e\\u0041\"",   // high surrogate followed by a non low surrogate
+        "\"\\udd8a\"",          // low surrogate on its own
+        "\"\\q\"",              // unknown escape
+        "\"\\u00g1\"",          // not a hexadecimal digit
+        "\"\\u00\"",            // truncated escape
+    };
+    for (const char* text : broken) {
+        JsonParseResult parsed = parseJson(text);
+        CHECK(!parsed.ok);
+        CHECK(parsed.error.present());
+        CHECK(!parsed.error.message.empty());
+    }
+}
+