diff --git a/meson.build b/meson.build
index 3b97bc9..08c324b 100644
--- a/meson.build
+++ b/meson.build
@@ -31,4 +31,5 @@ cpp = meson.get_compiler('cpp')
 subdir('assets/static')
 
 subdir('src')
+subdir('tests')
 
diff --git a/readme.md b/readme.md
index e69de29..cca6659 100644
--- a/readme.md
+++ b/readme.md
@@ -0,0 +1,5 @@
+# libconstants
+
+libconstants is the authoritative source for physical constants for the SERiF project.
+
+This has been broken out of the main serif project to allow for more modularity
diff --git a/subprojects/gtest.wrap b/subprojects/gtest.wrap
new file mode 100644
index 0000000..7b1e69e
--- /dev/null
+++ b/subprojects/gtest.wrap
@@ -0,0 +1,16 @@
+[wrap-file]
+directory = googletest-1.15.2
+source_url = https://github.com/google/googletest/archive/refs/tags/v1.15.2.tar.gz
+source_filename = gtest-1.15.2.tar.gz
+source_hash = 7b42b4d6ed48810c5362c265a17faebe90dc2373c885e5216439d37927f02926
+patch_filename = gtest_1.15.2-2_patch.zip
+patch_url = https://wrapdb.mesonbuild.com/v2/gtest_1.15.2-2/get_patch
+patch_hash = 641a16b33c96cd32a593537bc30eb7d853c5cc361fa1ee96884f0e2fca21e2d3
+source_fallback_url = https://github.com/mesonbuild/wrapdb/releases/download/gtest_1.15.2-2/gtest-1.15.2.tar.gz
+wrapdb_version = 1.15.2-2
+
+[provide]
+gtest = gtest_dep
+gtest_main = gtest_main_dep
+gmock = gmock_dep
+gmock_main = gmock_main_dep
diff --git a/tests/constants/constTest.cpp b/tests/constants/constTest.cpp
new file mode 100644
index 0000000..b458339
--- /dev/null
+++ b/tests/constants/constTest.cpp
@@ -0,0 +1,109 @@
+#include <gtest/gtest.h>
+#include "const.h"
+#include <iostream>
+#include <string>
+#include <vector>
+#include <set>
+#include <sstream>
+
+/**
+ * @file constTest.cpp
+ * @brief Unit tests for the const class.
+ */
+
+/**
+ * @brief Test suite for the const class.
+ */
+class constTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        serif::constant::Constants::getInstance();
+    }
+};
+
+/**
+ * @test Verify default constructor initializes correctly.
+ */
+TEST_F(constTest, DefaultConstructor) {
+    EXPECT_NO_THROW(serif::constant::Constants::getInstance());
+}
+
+/**
+ * @test Verify constructor initializes with provided data and metadata.
+ */
+TEST_F(constTest, isLoaded) {
+
+    EXPECT_NO_THROW(serif::constant::Constants::getInstance().isLoaded());
+}
+
+/**
+ * @test Verify get method returns the correct constant.
+ */
+TEST_F(constTest, GetMethod) {
+    serif::constant::Constants& obj = serif::constant::Constants::getInstance();
+    EXPECT_DOUBLE_EQ(obj.get("c").value, 2.99792458e10);
+    EXPECT_EQ(obj.get("c").unit, "cm / s");
+    EXPECT_DOUBLE_EQ(obj.get("c").uncertainty, 0.0);
+    EXPECT_EQ(obj.get("c").reference, "CODATA2022");
+}
+
+/**
+ * @test Verify [] opperators returns the correct constant.
+ */
+TEST_F(constTest, SubscriptOperator) {
+    serif::constant::Constants& obj = serif::constant::Constants::getInstance();
+    EXPECT_DOUBLE_EQ(obj["c"].value, 2.99792458e10);
+    EXPECT_EQ(obj["c"].unit, "cm / s");
+    EXPECT_DOUBLE_EQ(obj["c"].uncertainty, 0.0);
+    EXPECT_EQ(obj["c"].reference, "CODATA2022");
+}
+
+/**
+ * @test Verify that the has method returns the correct values
+ */
+TEST_F(constTest, HasMethod) {
+    serif::constant::Constants& obj = serif::constant::Constants::getInstance();
+
+    EXPECT_TRUE(obj.has("c"));
+    EXPECT_FALSE(obj.has("c4"));
+    EXPECT_TRUE(obj.has("hbar"));
+}
+
+TEST_F(constTest, KeysMethod) {
+    serif::constant::Constants& obj = serif::constant::Constants::getInstance();
+    std::set<std::string> checkKeys;
+    checkKeys.insert("c");
+    checkKeys.insert("wienK");
+    checkKeys.insert("hbar");
+    checkKeys.insert("g_h");
+    checkKeys.insert("R_sun");
+
+    std::set<std::string> keys = obj.keys();
+
+    for (const auto& key : checkKeys) {
+        bool found = keys.find(key) != keys.end();
+        EXPECT_TRUE(found);
+    }
+
+    std::set<std::string> checkBadKeys;
+    checkBadKeys.insert("c4");
+    checkBadKeys.insert("wienK4");
+    checkBadKeys.insert("hbar4");
+    checkBadKeys.insert("g_h4");
+    checkBadKeys.insert("R_sun4");
+
+    for (const auto& key : checkBadKeys) {
+        bool found = keys.find(key) != keys.end();
+        EXPECT_FALSE(found);
+    }
+}
+
+TEST_F(constTest, StreamOperator) {
+    serif::constant::Constants& obj = serif::constant::Constants::getInstance();
+    std::ostringstream os;
+
+    os << obj.get("c");
+    std::string expected = "<speed of light in vacuum: 2.99792e+10±0 cm / s (CODATA2022)>\n";
+
+    EXPECT_EQ(os.str(), expected);
+}
\ No newline at end of file
diff --git a/tests/constants/meson.build b/tests/constants/meson.build
new file mode 100644
index 0000000..53ec814
--- /dev/null
+++ b/tests/constants/meson.build
@@ -0,0 +1,22 @@
+# Test files for const
+test_sources = [
+    'constTest.cpp',
+]
+
+foreach test_file : test_sources
+  exe_name = test_file.split('.')[0]
+  message('Building test: ' + exe_name)
+
+  # Create an executable target for each test
+  test_exe = executable(
+      exe_name,
+      test_file,
+      dependencies: [gtest_dep, const_dep, gtest_main],
+      include_directories: include_directories('../../src/constants/public'),
+      link_with: libconst,  # Link the dobj library
+      install_rpath: '@loader_path/../../src'  # Ensure runtime library path resolves correctly
+  )
+
+  # Add the executable as a test
+  test(exe_name, test_exe)
+endforeach
diff --git a/tests/meson.build b/tests/meson.build
new file mode 100644
index 0000000..fc313c9
--- /dev/null
+++ b/tests/meson.build
@@ -0,0 +1,7 @@
+# Google Test dependency
+gtest_dep = dependency('gtest', main: true, required : true)
+gtest_main = dependency('gtest_main', required: true)
+gtest_nomain_dep = dependency('gtest', main: false, required : true)
+
+# Subdirectories for unit and integration tests
+subdir('constants')