readme on how to run the test

Author: analogrelay

sdk/cosmos/cosmosclient/c_tests/README.md

@@ -3,3 +3,42 @@
 This directory contains tests written in C that utilize the Cosmos Client library. The tests are designed to validate the functionality of the Cosmos Client C API, ensuring that it correctly interacts with the Azure CosmosDB service.
 
 Building this directory requires CMake, Rust, and a C compiler.
+
+## Running the tests
+
+To run the tests, follow these steps:
+
+1. Create a `build` directory:
+
+```bash
+mkdir build
+cd build
+```
+
+1. Configure the project with CMake:
+
+```bash
+cmake ..
+```
+
+1. Run the build AND tests:
+
+```bash
+make && make test
+```
+
+## Test Structure
+
+Each test is a separate C program located in the `c_tests` directory.
+The tests are compiled into executables that can be run independently.
+Tests must be manually listed in `CMakeLists.txt` to be included in the build process:
+
+```cmake
+set(TEST_FILES
+    ./c_tests/version.c
+    ./c_tests/your_test_here.c)
+```
+
+Once a test is present in the `TEST_FILES` list, it will be automatically compiled and linked against the Cosmos Client library (either static, or dynamic, depending on the value of `BUILD_SHARED_LIBS` when `cmake` is run, which defaults to `ON`).
+
+Helper code should be added to an include file in the `c_tests` directory, such as `c_tests/test_helpers.h`, and included in the test files as needed.