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+# How to write goc e2e test cases
+
+Current goc e2e test is based on the [bats-core](https://github.com/bats-core/bats-core) framework, you should read its document first.
+
+## Local dev requirements
+
+* [bats-core](https://github.com/bats-core/bats-core)
+* install `goc` to `PATH`
+* build `goc` with `goc`, generate the binary `gocc`, install `gocc` to `PATH`
+
+## Test goc
+
+First of all, you should start a `goc server` in `setup_file` function from the backend, 
+
+```
+setup_file() {
+    goc server 3>&- &
+    GOC_PID=$!
+    sleep 2
+    goc init
+}
+```
+
+According to [this](https://github.com/bats-core/bats-core/blob/master/README.md#file-descriptor-3-read-this-if-bats-hangs), you should turn off the file descriptor 3 for the long-running backend job. Then you can write any `goc` subcommand. Remember to kill the `$GOC_PID` in the `teardown_file` function.
+
+## Test covered goc - gocc
+
+We also need to test with the covered gocc in order to get coverage reports.
+
+Most gocc test cases share the same structure, here is the common flow diagram:
+
+```  
+  (1)                                       (2)                                     
+  (wait_profile_backend "xxx" &) --> wait ci-sync exist --> (goc profile -o filtered.cov)--
+                                            |                                             |
+                                            |                                             |
+                                            | (4)                                         |
+  --(gocc --debugcisyncfile ci-sync) --> finish, write ci-sync --> sleep 5; exit          |(5)
+  |                                                                        |              |
+  | (3)                                             (6)                    |              |
+  |------------------------>(goc server &) --------------------------------|              |
+                                  |                                                       |
+                                  ---------------------------------------------------------
+```
+
+1. start the `wait_profile_backend` in the background.
+2. `wait_profile_backend` will block until the file `ci-sync.bak` exists.
+3. the covered `gocc` subcommand start and register to the `goc server`.
+4. the covered `gocc` subcommand run its own logic until finish, as we add the `--debugcisyncfile ci-sync` flag, it will write a file called `ci-sync`, and wait 5 seconds.
+5. `wait_profile_backend` continue to run, and try to get the profile from the `goc server`.
+6. the `goc server` finally call the http API to get the `gocc` profile.