Reorganize directories (#3462)

* 🚚 move files
* 🚚 rename doc folder to docs
* 🚚 rename test folder to tests

tests/src/fuzzer-parse_json.cpp

@@ -0,0 +1,69 @@
+/*
+    __ _____ _____ _____
+ __|  |   __|     |   | |  JSON for Modern C++ (fuzz test support)
+|  |  |__   |  |  | | | |  version 3.10.5
+|_____|_____|_____|_|___|  https://github.com/nlohmann/json
+
+This file implements a parser test suitable for fuzz testing. Given a byte
+array data, it performs the following steps:
+
+- j1 = parse(data)
+- s1 = serialize(j1)
+- j2 = parse(s1)
+- s2 = serialize(j2)
+- assert(s1 == s2)
+
+The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
+drivers.
+
+Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+*/
+
+#include <iostream>
+#include <sstream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+// see http://llvm.org/docs/LibFuzzer.html
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+    try
+    {
+        // step 1: parse input
+        json j1 = json::parse(data, data + size);
+
+        try
+        {
+            // step 2: round trip
+
+            // first serialization
+            std::string s1 = j1.dump();
+
+            // parse serialization
+            json j2 = json::parse(s1);
+
+            // second serialization
+            std::string s2 = j2.dump();
+
+            // serializations must match
+            assert(s1 == s2);
+        }
+        catch (const json::parse_error&)
+        {
+            // parsing a JSON serialization must not fail
+            assert(false);
+        }
+    }
+    catch (const json::parse_error&)
+    {
+        // parse errors are ok, because input may be random bytes
+    }
+    catch (const json::out_of_range&)
+    {
+        // out of range errors may happen if provided sizes are excessive
+    }
+
+    // return 0 - non-zero return values are reserved for future use
+    return 0;
+}