by patrick.allen.higgins:

Running "go test pkg1 pkg2 pkg3" compiles and executes three separate test
binaries, one for each package. This behavior is implied by
http://golang.org/cmd/go/#hdr-Test_packages (particularly the -c flag docs imply the
package name is part of the binary) but is not explicit.

A "go test -x pkg1 pkg2 pkg3" makes the current behavior clear, but it's not
clear if this behavior is intentionally undefined.

Original discussion on golang-nuts:
https://groups.google.com/forum/?fromgroups=#!topic/golang-nuts/ta_LwdPrKwU