Fix and update testing documentation

Improve the testing documentation in the following ways:

1. Ensure all of the given commands actually work. Some of them
specified tests that no longer existed or packages that no longer had
tests.
2. Clarify the ability to run tests for a package and all its
subpackages with `/...`.
3. Clarify how the developer can also utilize `go test` if they desire.

contributors/devel/sig-testing/testing.md

@@ -46,13 +46,23 @@ passing, so it is often a good idea to make sure the e2e tests work as well.
 ### Run all unit tests
 
 `make test` is the entrypoint for running the unit tests that ensures that
-`GOPATH` is set up correctly.  If you have `GOPATH` set up correctly, you can
-also just use `go test` directly.
+`GOPATH` is set up correctly.
 
 ```sh
 cd kubernetes
 make test  # Run all unit tests.
 ```
+If you have `GOPATH` set up correctly, you can
+also just use `go test` directly.
+
+```sh
+cd kubernetes
+go test ./... # Run all unit tests
+```
+
+The remainder of this documentation presumes that you use `Make` as an
+entry point, but remember that the ability to use `go test` exists should you
+desire.
 
 If any unit test fails with a timeout panic (see [#1594](https://github.com/kubernetes/community/issues/1594)) on the testing package, you can increase the `KUBE_TIMEOUT` value as shown below.
 
@@ -71,19 +81,33 @@ You can set [go flags](https://golang.org/cmd/go/) by setting the
 added automatically to these:
 
 ```sh
-make test WHAT=./pkg/api                # run tests for pkg/api
+make test WHAT=./pkg/kubelet                # run tests for pkg/kubelet
+```
+
+Expressed strictly with `go test`, the above command is equivalent to the following:
+
+```sh
+go test ./pkg/kubelet
+```
+
+To run tests for a package and all of its subpackages, you need to append `...`
+to the package path:
+
+```sh
+make test WHAT=./pkg/api/...  # run tests for pkg/api and all its subpackages
 ```
 
 To run multiple targets you need quotes:
 
 ```sh
-make test WHAT="./pkg/api ./pkg/kubelet"  # run tests for pkg/api and pkg/kubelet
+make test WHAT="./pkg/kubelet ./pkg/scheduler"  # run tests for pkg/kubelet and pkg/scheduler
 ```
 
 In a shell, it's often handy to use brace expansion:
 
 ```sh
-make test WHAT=./pkg/{api,kubelet}  # run tests for pkg/api and pkg/kubelet
+make test WHAT=./pkg/{kubelet,scheduler}  # run tests for pkg/kubelet and
+pkg/scheduler
 ```
 
 ### Run specific unit test cases in a package
@@ -94,10 +118,16 @@ regular expression for the name of the test that should be run.
 
 ```sh
 # Runs TestValidatePod in pkg/api/validation with the verbose flag set
-make test WHAT=./pkg/api/validation GOFLAGS="-v" KUBE_TEST_ARGS='-run ^TestValidatePod$'
+make test WHAT=./pkg/apis/core/validation GOFLAGS="-v" KUBE_TEST_ARGS='-run ^TestValidatePod$'
 
 # Runs tests that match the regex ValidatePod|ValidateConfigMap in pkg/api/validation
-make test WHAT=./pkg/api/validation GOFLAGS="-v" KUBE_TEST_ARGS="-run ValidatePod\|ValidateConfigMap$"
+make test WHAT=./pkg/apis/core/validation GOFLAGS="-v" KUBE_TEST_ARGS="-run ValidatePod\|ValidateConfigMap$"
+```
+
+Or if we are using `go test` as our entry point, we could run:
+
+```sh
+go test ./pkg/apis/core/validation -v -run ^TestValidatePods$
 ```
 
 For other supported test flags, see the [golang
@@ -143,14 +173,23 @@ combined for all tests run.
 To run benchmark tests, you'll typically use something like:
 
 ```sh
-go test ./pkg/apiserver -benchmem -run=XXX -bench=BenchmarkWatch
+make test WHAT=./pkg/scheduler/internal/cache KUBE_TEST_ARGS='-benchmem -run=XXX -bench=BenchmarkExpirePods'
+```
+
+Alternatively, to express in pure Go, you could write the following:
+
+```sh
+go test ./pkg/scheduler/internal/cache -benchmem -run=XXX -bench=Benchmark
 ```
 
 This will do the following:
 
-1. `-run=XXX` is a regular expression filter on the name of test cases to run
-2. `-bench=BenchmarkWatch` will run test methods with BenchmarkWatch in the name
-  * See `grep -nr BenchmarkWatch .` for examples
+1. `-run=XXX` is a regular expression filter on the name of test cases to run.
+   Go will execute both the tests matching the `-bench` regex and the `-run`
+   regex. Since we only want to execute benchmark tests, we set the `-run` regex
+   to XXX, which will not match any tests.
+2. `-bench=Benchmark` will run test methods with Benchmark in the name
+  * See `grep -nr Benchmark .` for examples
 3. `-benchmem` enables memory allocation stats
 
 See `go help test` and `go help testflag` for additional info.