Move unit tests to the location Meson expects them to be

Everything that is a separate subproject should live in the subprojects
directory.

Progress on #2503

This reverts commit 451f8a8c19.

src/libutil-tests/nix_api_util.cc

@@ -0,0 +1,144 @@
+#include "config-global.hh"
+#include "args.hh"
+#include "nix_api_util.h"
+#include "nix_api_util_internal.h"
+#include "tests/nix_api_util.hh"
+#include "tests/string_callback.hh"
+
+#include <gtest/gtest.h>
+
+namespace nixC {
+
+TEST_F(nix_api_util_context, nix_context_error)
+{
+    std::string err_msg_ref;
+    try {
+        throw nix::Error("testing error");
+    } catch (nix::Error & e) {
+        err_msg_ref = e.what();
+        nix_context_error(ctx);
+    }
+    ASSERT_EQ(ctx->last_err_code, NIX_ERR_NIX_ERROR);
+    ASSERT_EQ(ctx->name, "nix::Error");
+    ASSERT_EQ(*ctx->last_err, err_msg_ref);
+    ASSERT_EQ(ctx->info->msg.str(), "testing error");
+
+    try {
+        throw std::runtime_error("testing exception");
+    } catch (std::exception & e) {
+        err_msg_ref = e.what();
+        nix_context_error(ctx);
+    }
+    ASSERT_EQ(ctx->last_err_code, NIX_ERR_UNKNOWN);
+    ASSERT_EQ(*ctx->last_err, err_msg_ref);
+
+    nix_clear_err(ctx);
+    ASSERT_EQ(ctx->last_err_code, NIX_OK);
+}
+
+TEST_F(nix_api_util_context, nix_set_err_msg)
+{
+    ASSERT_EQ(ctx->last_err_code, NIX_OK);
+    nix_set_err_msg(ctx, NIX_ERR_UNKNOWN, "unknown test error");
+    ASSERT_EQ(ctx->last_err_code, NIX_ERR_UNKNOWN);
+    ASSERT_EQ(*ctx->last_err, "unknown test error");
+}
+
+TEST(nix_api_util, nix_version_get)
+{
+    ASSERT_EQ(std::string(nix_version_get()), PACKAGE_VERSION);
+}
+
+struct MySettings : nix::Config
+{
+    nix::Setting<std::string> settingSet{this, "empty", "setting-name", "Description"};
+};
+
+MySettings mySettings;
+static nix::GlobalConfig::Register rs(&mySettings);
+
+TEST_F(nix_api_util_context, nix_setting_get)
+{
+    ASSERT_EQ(ctx->last_err_code, NIX_OK);
+    std::string setting_value;
+    nix_err result = nix_setting_get(ctx, "invalid-key", OBSERVE_STRING(setting_value));
+    ASSERT_EQ(result, NIX_ERR_KEY);
+
+    result = nix_setting_get(ctx, "setting-name", OBSERVE_STRING(setting_value));
+    ASSERT_EQ(result, NIX_OK);
+    ASSERT_STREQ("empty", setting_value.c_str());
+}
+
+TEST_F(nix_api_util_context, nix_setting_set)
+{
+    nix_err result = nix_setting_set(ctx, "invalid-key", "new-value");
+    ASSERT_EQ(result, NIX_ERR_KEY);
+
+    result = nix_setting_set(ctx, "setting-name", "new-value");
+    ASSERT_EQ(result, NIX_OK);
+
+    std::string setting_value;
+    result = nix_setting_get(ctx, "setting-name", OBSERVE_STRING(setting_value));
+    ASSERT_EQ(result, NIX_OK);
+    ASSERT_STREQ("new-value", setting_value.c_str());
+}
+
+TEST_F(nix_api_util_context, nix_err_msg)
+{
+    // no error
+    EXPECT_THROW(nix_err_msg(nullptr, ctx, NULL), nix::Error);
+
+    // set error
+    nix_set_err_msg(ctx, NIX_ERR_UNKNOWN, "unknown test error");
+
+    // basic usage
+    std::string err_msg = nix_err_msg(NULL, ctx, NULL);
+    ASSERT_EQ(err_msg, "unknown test error");
+
+    // advanced usage
+    unsigned int sz;
+    err_msg = nix_err_msg(nix_c_context_create(), ctx, &sz);
+    ASSERT_EQ(sz, err_msg.size());
+}
+
+TEST_F(nix_api_util_context, nix_err_info_msg)
+{
+    std::string err_info;
+
+    // no error
+    EXPECT_THROW(nix_err_info_msg(NULL, ctx, OBSERVE_STRING(err_info)), nix::Error);
+
+    try {
+        throw nix::Error("testing error");
+    } catch (...) {
+        nix_context_error(ctx);
+    }
+    nix_err_info_msg(nix_c_context_create(), ctx, OBSERVE_STRING(err_info));
+    ASSERT_STREQ("testing error", err_info.c_str());
+}
+
+TEST_F(nix_api_util_context, nix_err_name)
+{
+    std::string err_name;
+
+    // no error
+    EXPECT_THROW(nix_err_name(NULL, ctx, OBSERVE_STRING(err_name)), nix::Error);
+
+    std::string err_msg_ref;
+    try {
+        throw nix::Error("testing error");
+    } catch (...) {
+        nix_context_error(ctx);
+    }
+    nix_err_name(nix_c_context_create(), ctx, OBSERVE_STRING(err_name));
+    ASSERT_EQ(std::string(err_name), "nix::Error");
+}
+
+TEST_F(nix_api_util_context, nix_err_code)
+{
+    ASSERT_EQ(nix_err_code(ctx), NIX_OK);
+    nix_set_err_msg(ctx, NIX_ERR_UNKNOWN, "unknown test error");
+    ASSERT_EQ(nix_err_code(ctx), NIX_ERR_UNKNOWN);
+}
+
+}