Add README for integration test (#24441)

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

tests/integration/README.md

@@ -0,0 +1,70 @@
+# Integration test
+
+This folder contains the integration test for Milvus components.
+
+## How to run integration test locally
+
+Integration test still need some thirdparty components to start:
+
+```bash
+cd [milvus-folder]/deployments/docker/dev && docker-compose up -d
+```
+
+Run following script to start the full integration test:
+```bash
+cd [milvus-folder]
+make milvus # milvus needs to be compiled to make cpp build ready
+./scripts/run_intergration_test.sh
+```
+
+If you want to run single test case, you could execute command like this example
+
+```bash
+# mq, etcd, minio ready before
+cd [milvus-folder]
+source scripts/setenv.sh
+cd tests/integration/[testcase-folder]/
+go test -run "$testCaseName^" -testify.m "$subTestifyCaseName^" -race -v
+```
+
+## Recommended coding style for add new cases
+
+
+### Using `suite`
+
+MiniCluster` and `MiniClusterSuite` provides lots of comment preset tool function to execute intergration test.
+
+It is recommend to add a new test with `testify/suite`
+
+```go
+
+import (
+    // ...
+    "github.com/milvus-io/milvus/tests/integration"
+)
+
+type NewSuite struct {
+    integration.MiniClusterSuite
+}
+
+
+// Setups and teardowns, optional if no custom logic needed
+// example to suite setup & teardown, same logic applies to test setup&teardown
+
+func (s *NewSuite) SetupSuite() {
+    s.MiniClusterSuite.SetupSuite()
+    // customized setup
+}
+
+func (s *NewSuite) TearDownSuite() {
+    s.MiniClusterSuite.TearDownSuite()
+    // customized teardown
+}
+
+```
+
+### New folder for each new scenario
+
+It's a known issue that integration test cases run in same process might affect due to some singleton component not fully cleaned.
+
+As a temp solution, test cases are separated into different packages to run independently.