Add TESTING document.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

TESTING.md

@@ -0,0 +1,87 @@
+# Testing
+
+The following guidelines summarize the testing policy for docker/cli.
+
+## Unit Test Suite
+
+All code changes should have unit test coverage.
+
+Error cases should be tested with unit tests.
+
+Bug fixes should be covered by new unit tests or additional assertions in
+existing unit tests.
+
+### Details
+
+The unit test suite follows the standard Go testing convention. Tests are
+located in the package directory in `_test.go` files.
+
+Unit tests should be named using the convention:
+
+```
+Test<Function Name><Test Case Name>
+```
+
+[Table tests](https://github.com/golang/go/wiki/TableDrivenTests) should be used
+where appropriate, but may not be appropriate in all cases.
+
+Assertions should be made using
+[testify/assert](https://godoc.org/github.com/stretchr/testify/assert) and test
+requirements should be verified using
+[testify/require](https://godoc.org/github.com/stretchr/testify/require).
+
+Fakes, and testing utilities can be found in
+[internal/test](https://godoc.org/github.com/docker/cli/internal/test) and
+[gotestyourself](https://godoc.org/github.com/gotestyourself/gotestyourself).
+
+## End-to-End Test Suite
+
+The end-to-end test suite tests a cli binary against a real API backend.
+
+### Guidelines
+
+Each feature (subcommand) should have a single end-to-end test for 
+the success case. The test should include all (or most) flags/options supported
+by that feature.
+
+In some rare cases a couple additional end-to-end tests may be written for a
+sufficiently complex and critical feature (ex: `container run`, `service 
+create`, `service update`, and `docker build` may have ~3-5 cases each).
+
+In some rare cases a sufficiently critical error paths may have a single
+end-to-end test case.
+
+In all other cases the behaviour should be covered by unit tests.
+
+If a code change adds a new flag, that flag should be added to the existing 
+"success case" end-to-end test.
+
+If a code change fixes a bug, that bug fix should be covered either by adding 
+assertions to the existing end-to-end test, or with one or more unit test.
+
+### Details
+
+The end-to-end test suite is located in
+[./e2e](https://github.com/docker/cli/tree/master/e2e). Each directory in `e2e`
+corresponds to a directory in `cli/command` and contains the tests for that
+subcommand. Files in each directory should be named `<command>_test.go` where
+command is the basename of the command (ex: the test for `docker stack deploy`
+is found in `e2e/stack/deploy_test.go`).
+
+Tests should be named using the convention:
+
+```
+Test<Command Basename>[<Test Case Name>]
+```
+
+where the test case name is only required when there are multiple test cases for
+a single command.
+
+End-to-end test should run the `docker` binary using
+[gotestyourself/icmd](https://godoc.org/github.com/gotestyourself/gotestyourself/icmd)
+and make assertions about the exit code, stdout, stderr, and local file system.
+
+Any Docker image or registry operations should use `registry:5000/<image name>`
+to communicate with the local instance of the Docker registry. To load 
+additional fixture images to the registry see
+[scripts/test/e2e/run](https://github.com/docker/cli/blob/master/scripts/test/e2e/run).

internal/test/doc.go

@@ -1,5 +1,5 @@
 // Package test is a test-only package that can be used by other cli package to write unit test.
 //
-// It as an internal package and cannot be used outside of github.com/docker/cli/cli package.
+// It as an internal package and cannot be used outside of github.com/docker/cli package.
 //
 package test