Setup for inclusion in the Bazel Central Registry

By adding a MODULE.bazel file, this library becomes usable with Bazel's
new external dependency management system Bzlmod.

The new tests are run when a new version is included in the Bazel
Central Registry and verify that the basic functionality works with the
provided Bazel setup.

See:
https://bazel.build/build/bzlmod

.gitignore

@@ -20,6 +20,7 @@
 
 # build directories (vscode-cmake-tools, user-defined, ...)
 /build*/
+bazel-*
 
 # fuzzers
 /tests/corpus_*

MODULE.bazel

@@ -0,0 +1,5 @@
+module(
+    name = "nlohmann_json",
+    compatibility_level = 1,
+    version = "3.11.2",
+)

tests/bazel/.bazelrc

@@ -0,0 +1 @@
+common --enable_bzlmod

tests/bazel/.bazelversion

@@ -0,0 +1 @@
+6.0.0rc1

tests/bazel/BUILD.bazel

@@ -0,0 +1,5 @@
+cc_test(
+    name = "json_example_test",
+    srcs = ["json_example_test.cpp"],
+    deps = ["@json"],
+)

tests/bazel/MODULE.bazel

@@ -0,0 +1,5 @@
+bazel_dep(name = "nlohmann_json", repo_name = "json")
+local_path_override(
+    module_name = "nlohmann_json",
+    path = "../.."
+)

tests/bazel/WORKSPACE.bzlmod

@@ -0,0 +1,2 @@
+# The presence of this file ensures that Bazel ignores WORKSPACE.bazel and
+# does not implicitly add any dependency declarations.

tests/bazel/json_example_test.cpp

@@ -0,0 +1,24 @@
+#include <iostream>
+#include <string>
+
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::json j;
+    j["pi"] = 3.141;
+    j["happy"] = true;
+    j["name"] = "Niels";
+    j["nothing"] = nullptr;
+    j["answer"]["everything"] = 42;
+    j["list"] = {1, 0, 2};
+    j["object"] = {{"currency", "USD"}, {"value", 42.99}};
+
+    std::string s = j.dump();
+    if (s != R"({"answer":{"everything":42},"happy":true,"list":[1,0,2],"name":"Niels","nothing":null,"object":{"currency":"USD","value":42.99},"pi":3.141})")
+    {
+        std::cerr << "Unexpected JSON serialization: " << s << std::endl;
+        return 1;
+    }
+    return 0;
+}