Add instructions to run unit tests locally (#256)

README.md

@@ -16,3 +16,45 @@ You can find all the commands documented [here](https://docs.yugabyte.com/previe
 
 You can find the example workflows documented [here](https://docs.yugabyte.com/preview/yugabyte-cloud/managed-automation/managed-cli/managed-cli-examples/)
 
+## Running unit tests locally:
+This project uses [GinkGo](https://onsi.github.io/ginkgo/) for testing.
+
+### Pre-requisite
+- **Golang** must be installed on your machine.
+
+### Running All Tests:
+To run all the tests, navigate to the `cmd` directory and use the following command:
+
+```bash
+# This is mandatory, if you run $ go test from root of your project, it will run 0 tests.
+cd cmd
+
+# Run all tests
+go test
+```
+
+### Running tests in a file:
+You need to first install ginkgo via:
+```bash
+go install github.com/onsi/ginkgo/v2/ginkgo
+```
+
+This will install ginkgo where `go` is installed e.g. `/Users/alice/go/`. You can check the go installation path by running `go env GOPATH`. It's generally at `$HOME/go`.
+
+To run a test, go to the directory where your test resides i.e. `ybm-cli/cmd` in this case.
+
+If your tests in a file say `cluster_test.go` are like this.
+```go 
+var _ = Describe("Cluster", func() {
+    Describe("Pausing cluster", func() { ... }
+    Describe("Resuming cluster", func() { ... }
+    Describe("Get Cluster", func() { ... }
+}
+```
+
+You can run the tests like:
+```bash
+$HOME/go/bin/ginkgo -v -focus="Cluster" # To run all tests related to Cluster.
+$HOME/go/bin/ginkgo -v -focus="Pausing cluster|Resuming cluster" # To run all tests related to Pausing/Resuming cluster
+```
+It can be a regex as well inside focus or text from either of `Context`, `It` or `Describe` block. You can read more about it [here](https://onsi.github.io/ginkgo/#description-based-filtering).