diff --git a/src/lib/support/tests/BUILD.gn b/src/lib/support/tests/BUILD.gn
index ee1af161003649..f85bf6c5d3e25f 100644
--- a/src/lib/support/tests/BUILD.gn
+++ b/src/lib/support/tests/BUILD.gn
@@ -29,6 +29,7 @@ chip_test_suite("tests") {
     "TestCHIPArgParser.cpp",
     "TestCHIPCounter.cpp",
     "TestCHIPMem.cpp",
+    "TestCHIPMemString.cpp",
     "TestDefer.cpp",
     "TestErrorStr.cpp",
     "TestFixedBufferAllocator.cpp",
diff --git a/src/lib/support/tests/TestCHIPMemString.cpp b/src/lib/support/tests/TestCHIPMemString.cpp
new file mode 100644
index 00000000000000..f887995079f9b8
--- /dev/null
+++ b/src/lib/support/tests/TestCHIPMemString.cpp
@@ -0,0 +1,166 @@
+/*
+ *
+ *    Copyright (c) 2021 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#include <inttypes.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <lib/support/CHIPMemString.h>
+#include <lib/support/CodeUtils.h>
+#include <lib/support/ScopedBuffer.h>
+#include <lib/support/Span.h>
+#include <lib/support/UnitTestRegistration.h>
+#include <nlunit-test.h>
+
+using namespace chip;
+using namespace chip::Platform;
+
+// =================================
+//      Unit tests
+// =================================
+
+namespace {
+template <size_t kTestBufLen>
+struct TestBuffers
+{
+    char correctSizeBuf[kTestBufLen];
+    char tooSmallBuf[kTestBufLen - 1];
+    char wayTooSmallBuf[1];
+    char tooBigBuf[kTestBufLen + 10];
+    void Reset()
+    {
+        memset(correctSizeBuf, 1, sizeof(correctSizeBuf));
+        memset(tooSmallBuf, 1, sizeof(tooSmallBuf));
+        memset(wayTooSmallBuf, 1, sizeof(wayTooSmallBuf));
+        memset(tooBigBuf, 1, sizeof(tooBigBuf));
+    }
+    void CheckCorrectness(nlTestSuite * inSuite, const char * testStr)
+    {
+        // correctSizeBuf and tooBigBuf should have the complete string.
+        NL_TEST_ASSERT(inSuite, correctSizeBuf[kTestBufLen - 1] == '\0');
+        NL_TEST_ASSERT(inSuite, tooBigBuf[kTestBufLen - 1] == '\0');
+        NL_TEST_ASSERT(inSuite, strcmp(correctSizeBuf, testStr) == 0);
+        NL_TEST_ASSERT(inSuite, strcmp(tooBigBuf, testStr) == 0);
+        NL_TEST_ASSERT(inSuite, strlen(correctSizeBuf) == strlen(testStr));
+        NL_TEST_ASSERT(inSuite, strlen(tooBigBuf) == strlen(testStr));
+
+        // wayTooSmallBuf is tiny and thus will only have the null terminator
+        NL_TEST_ASSERT(inSuite, wayTooSmallBuf[0] == '\0');
+
+        // tooSmallBuf should still have a null terminator on the end
+        NL_TEST_ASSERT(inSuite, tooSmallBuf[kTestBufLen - 2] == '\0');
+        NL_TEST_ASSERT(inSuite, memcmp(tooSmallBuf, testStr, kTestBufLen - 2) == 0);
+    }
+};
+
+} // namespace
+
+static void TestCopyString(nlTestSuite * inSuite, void * inContext)
+{
+    constexpr char testWord[] = "testytest";
+    ByteSpan testWordSpan     = ByteSpan(reinterpret_cast<const uint8_t *>(testWord), sizeof(testWord) - 1);
+    TestBuffers<sizeof(testWord)> testBuffers;
+
+    // CopyString with explicit size
+    testBuffers.Reset();
+    CopyString(testBuffers.correctSizeBuf, sizeof(testBuffers.correctSizeBuf), testWord);
+    CopyString(testBuffers.tooSmallBuf, sizeof(testBuffers.tooSmallBuf), testWord);
+    CopyString(testBuffers.wayTooSmallBuf, sizeof(testBuffers.wayTooSmallBuf), testWord);
+    CopyString(testBuffers.tooBigBuf, sizeof(testBuffers.tooBigBuf), testWord);
+    testBuffers.CheckCorrectness(inSuite, testWord);
+
+    // CopyString with array size
+    testBuffers.Reset();
+    CopyString(testBuffers.correctSizeBuf, testWord);
+    CopyString(testBuffers.tooSmallBuf, testWord);
+    CopyString(testBuffers.wayTooSmallBuf, testWord);
+    CopyString(testBuffers.tooBigBuf, testWord);
+    testBuffers.CheckCorrectness(inSuite, testWord);
+
+    // CopyString with explicit size from ByteSpan
+    testBuffers.Reset();
+    CopyString(testBuffers.correctSizeBuf, sizeof(testBuffers.correctSizeBuf), testWordSpan);
+    CopyString(testBuffers.tooSmallBuf, sizeof(testBuffers.tooSmallBuf), testWordSpan);
+    CopyString(testBuffers.wayTooSmallBuf, sizeof(testBuffers.wayTooSmallBuf), testWordSpan);
+    CopyString(testBuffers.tooBigBuf, sizeof(testBuffers.tooBigBuf), testWordSpan);
+    testBuffers.CheckCorrectness(inSuite, testWord);
+
+    // CopyString with array size from ByteSpan
+    testBuffers.Reset();
+    CopyString(testBuffers.correctSizeBuf, testWordSpan);
+    CopyString(testBuffers.tooSmallBuf, testWordSpan);
+    CopyString(testBuffers.wayTooSmallBuf, testWordSpan);
+    CopyString(testBuffers.tooBigBuf, testWordSpan);
+    testBuffers.CheckCorrectness(inSuite, testWord);
+}
+
+static void TestMemoryAllocString(nlTestSuite * inSuite, void * inContext)
+{
+    constexpr char testStr[] = "testytestString";
+    char * allocatedStr      = MemoryAllocString(testStr, sizeof(testStr));
+    NL_TEST_ASSERT(inSuite, allocatedStr != nullptr);
+    if (allocatedStr == nullptr)
+    {
+        return;
+    }
+    NL_TEST_ASSERT(inSuite, strcmp(testStr, allocatedStr) == 0);
+    MemoryFree(allocatedStr);
+}
+
+static void TestScopedBuffer(nlTestSuite * inSuite, void * inContext)
+{
+    // Scoped buffer has its own tests that check the memory properly. Here we are just testing that the string is copied in
+    // properly.
+    constexpr char testStr[]        = "testytestString";
+    ScopedMemoryString scopedString = ScopedMemoryString(testStr, sizeof(testStr));
+    NL_TEST_ASSERT(inSuite, strcmp(scopedString.Get(), testStr) == 0);
+}
+
+static const nlTest sTests[] = { NL_TEST_DEF("Test CopyString", TestCopyString),
+                                 NL_TEST_DEF("Test MemoryAllocString", TestMemoryAllocString),
+                                 NL_TEST_DEF("Test ScopedBuffer", TestScopedBuffer), NL_TEST_SENTINEL() };
+
+int TestMemString_Setup(void * inContext)
+{
+    CHIP_ERROR error = MemoryInit();
+    if (error != CHIP_NO_ERROR)
+        return (FAILURE);
+    return (SUCCESS);
+}
+
+/**
+ *  Tear down the test suite.
+ */
+int TestMemString_Teardown(void * inContext)
+{
+    MemoryShutdown();
+    return (SUCCESS);
+}
+
+int TestMemString()
+{
+    nlTestSuite theSuite = { "CHIP Memory Allocation tests", &sTests[0], TestMemString_Setup, TestMemString_Teardown };
+
+    // Run test suit againt one context.
+    nlTestRunner(&theSuite, nullptr);
+    return nlTestRunnerStats(&theSuite);
+}
+
+CHIP_REGISTER_TEST_SUITE(TestMemString)