diff --git a/tests/meson.build b/tests/meson.build
index e68b8a2..45693ff 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -5,6 +5,7 @@ gtest_nomain_dep = dependency('gtest', main: false, required : true)
 # Subdirectories for unit and integration tests
 subdir('dobj')
 subdir('const')
+subdir('opatIO')
 
 # Subdirectories for sandbox tests
 subdir('dobj_sandbox')
diff --git a/tests/opatIO/example.opat b/tests/opatIO/example.opat
new file mode 100755
index 0000000..7b7e918
Binary files /dev/null and b/tests/opatIO/example.opat differ
diff --git a/tests/opatIO/meson.build b/tests/opatIO/meson.build
new file mode 100644
index 0000000..8722176
--- /dev/null
+++ b/tests/opatIO/meson.build
@@ -0,0 +1,27 @@
+# Test files for opatIO
+test_sources = [
+    'opatIOTest.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],
+      include_directories: include_directories('../../src/opatIO/public'),
+      link_with: libopatIO,  # 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,
+    env: ['MESON_SOURCE_ROOT=' + meson.project_source_root(), 'MESON_BUILD_ROOT=' + meson.project_build_root()])
+endforeach
diff --git a/tests/opatIO/opatIOTest.cpp b/tests/opatIO/opatIOTest.cpp
new file mode 100644
index 0000000..2356ff7
--- /dev/null
+++ b/tests/opatIO/opatIOTest.cpp
@@ -0,0 +1,78 @@
+#include <gtest/gtest.h>
+#include "opatIO.h"
+#include <iostream>
+#include <string>
+#include <vector>
+#include <set>
+#include <sstream>
+
+std::string EXAMPLE_FILENAME = std::string(getenv("MESON_SOURCE_ROOT")) + "/tests/opatIO/example.opat";
+
+class TestableOpatIO : public OpatIO {
+public:
+    using OpatIO::flushQueue;
+};
+/**
+ * @file opatIOTest.cpp
+ * @brief Unit tests for the OpatIO class and associated structs.
+ */
+
+/**
+ * @brief Test suite for the const class.
+ */
+class opatIOTest : public ::testing::Test {
+};
+
+/**
+ * @test Verify default constructor initializes correctly.
+ */
+TEST_F(opatIOTest, DefaultConstructor) {
+    EXPECT_NO_THROW(OpatIO());
+}
+
+/* 
+ * @test Verify constructor initializes correctly with a file.
+ */
+TEST_F(opatIOTest, Constructor) {
+    OpatIO opatIO(EXAMPLE_FILENAME);
+}
+
+TEST_F(opatIOTest, Header) {
+    OpatIO opatIO(EXAMPLE_FILENAME);
+    Header header = opatIO.getHeader();
+    EXPECT_EQ(header.version, 1);
+    EXPECT_EQ(header.numTables, 20);
+    EXPECT_EQ(header.headerSize, 256);
+    EXPECT_EQ(header.indexOffset, 417856);
+    EXPECT_EQ(std::string(header.creationDate), "Feb 14, 2025");
+    EXPECT_EQ(std::string(header.sourceInfo), "MESA 12700, Synthetic Opacity Data");
+    EXPECT_EQ(std::string(header.comment), "log10 kappa (cm^2/g)");
+}
+
+TEST_F(opatIOTest, TableIndex) {
+    OpatIO opatIO(EXAMPLE_FILENAME);
+    std::vector<TableIndex> tableIndex = opatIO.getTableIndex();
+    EXPECT_EQ(tableIndex.size(), 20);
+    EXPECT_EQ(tableIndex[0].X, 0.1);
+    EXPECT_EQ(tableIndex[0].Z, 0.001);
+    EXPECT_EQ(tableIndex[0].byteStart, 1696);
+    EXPECT_EQ(tableIndex[0].byteEnd, 22504);
+}
+
+TEST_F(opatIOTest, MaxQDepth) {
+    OpatIO opatIO(EXAMPLE_FILENAME);
+    EXPECT_EQ(opatIO.getMaxQDepth(), 10);
+    opatIO.setMaxQDepth(5);
+    EXPECT_EQ(opatIO.getMaxQDepth(), 5);
+}
+
+TEST_F(opatIOTest, unload){
+    OpatIO opatIO(EXAMPLE_FILENAME);
+    EXPECT_NO_THROW(opatIO.unload());
+    EXPECT_FALSE(opatIO.isLoaded());
+}
+
+TEST_F(opatIOTest, FlushQueue){
+    TestableOpatIO opatIO;
+    EXPECT_NO_THROW(opatIO.flushQueue());
+}
\ No newline at end of file