为什么“ go test -v”看不到GOPATH或GOPATH但“ go env”却看到？

The application works fine when I run it locally with: $ dev_appserver.py app.yaml

However, when I attempt to run tests, the ENV doesn't seem to be set.

$ go test -v

skincare.go:6:5: cannot find package "appengine" in any of:
    /usr/local/go/src/appengine (from $GOROOT)
    /Users/bryan/go/src/appengine (from $GOPATH)
skincare.go:7:5: cannot find package "appengine/datastore" in any of:
    /usr/local/go/src/appengine/datastore (from $GOROOT)
    /Users/bryan/go/src/appengine/datastore (from $GOPATH)
skincare.go:8:5: cannot find package "appengine/user" in any of:
    /usr/local/go/src/appengine/user (from $GOROOT)
    /Users/bryan/go/src/appengine/user (from $GOPATH)

$ go env

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/bryan/go/"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GO15VENDOREXPERIMENT="1"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
CXX="clang++"
CGO_ENABLED="1"

$GOPATH should not not contain the src part of the path. So instead of pointing to /Users/bryan/go/src/ it should point to /Users/bryan/go.

I suspect your tests are failing because you're invoking them directly with go test rather than using the App Engine SDK's test runner, goapp test, which will link you to the appengine package when it runs.