cmd/go: fix tests when go.env sets GOPROXY=direct GOSUMDB=off

Tested locally by changing GOROOT/go.env. At some point perhaps we
should also set up a builder that runs with some common expected
modifications to go.env
(such as GOTOOLCHAIN=local GOPROXY=direct GOSUMDB=off).

Fixes #61358.
Updates #61359.

Change-Id: I365ec536bec86370e302fb726fa897400ab42cf3
Reviewed-on: https://go-review.googlesource.com/c/go/+/509637
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Russ Cox <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
Auto-Submit: Bryan Mills <[email protected]>

src/cmd/go/scriptconds_test.go

@@ -49,6 +49,7 @@ func scriptConditions() map[string]script.Cond {
  add("git", lazyBool("the 'git' executable exists and provides the standard CLI", hasWorkingGit))
  add("GODEBUG", script.PrefixCondition("GODEBUG contains <suffix>", hasGodebug))
  add("GOEXPERIMENT", script.PrefixCondition("GOEXPERIMENT <suffix> is enabled", hasGoexperiment))
+ add("go-builder", script.BoolCondition("GO_BUILDER_NAME is non-empty", testenv.Builder() != ""))
  add("link", lazyBool("testenv.HasLink()", testenv.HasLink))
  add("mismatched-goroot", script.Condition("test's GOROOT_FINAL does not match the real GOROOT", isMismatchedGoroot))
  add("msan", sysCondition("-msan", platform.MSanSupported, true))

src/cmd/go/testdata/script/README

@@ -398,6 +398,8 @@ The available conditions are:
  GOOS/GOARCH supports -fuzz with instrumentation
 [git]
  the 'git' executable exists and provides the standard CLI
+[go-builder]
+ GO_BUILDER_NAME is non-empty
 [link]
  testenv.HasLink()
 [mismatched-goroot]

src/cmd/go/testdata/script/gotoolchain_net.txt

@@ -43,11 +43,13 @@ env GOSUMDB=$oldsumdb
 # Test a real GOTOOLCHAIN
 [short] skip
 [!net:golang.org] skip
+[!net:sum.golang.org] skip
 [!GOOS:darwin] [!GOOS:windows] [!GOOS:linux] skip
 [!GOARCH:amd64] [!GOARCH:arm64] skip
 
 env GOPROXY=
-env GOSUMDB=
+[go-builder] env GOSUMDB=
+[!go-builder] env GOSUMDB=sum.golang.org # Set explicitly in case GOROOT/go.env is modified.
 env GOTOOLCHAIN=go1.20.1
 
  # Avoid resolving a "go1.20.1" from the user's real $PATH.

src/cmd/go/testdata/script/gotoolchain_version.txt

@@ -1,6 +1,15 @@
-[!net:golang.org] skip
+[!net:proxy.golang.org] skip
 
-env GOPROXY=
+ # In the Go project's official release GOPROXY defaults to proxy.golang.org,
+ # but it may be changed in GOROOT/go.env (such as in third-party
+ # distributions).
+ #
+ # Make sure it is in use here, because the server for releases not served
+ # through the proxy (https://golang.org/toolchain?go-get=1) currently only
+ # serves the latest patch release for each of the supported stable releases.
+
+[go-builder] env GOPROXY=
+[!go-builder] env GOPROXY=https://proxy.golang.org
 
 go list -m -versions go
 stdout 1.20.1 # among others

src/cmd/go/testdata/script/mod_prefer_compatible.txt

@@ -10,9 +10,9 @@ env GOPROXY=
 env GOSUMDB=
 
 # github.com/russross/blackfriday v2.0.0+incompatible exists,
-# and should be resolved if we ask for v2.0 explicitly.
+# and should be resolved if we ask for it explicitly.
 
-go list -m github.com/russross/[email protected]
+go list -m github.com/russross/[email protected].0+incompatible
 stdout '^github.com/russross/blackfriday v2\.0\.0\+incompatible$'
 
 # blackfriday v1.5.2 has a go.mod file, so v1.5.2 should be preferred over
@@ -27,6 +27,7 @@ stdout '^github.com/russross/blackfriday v1\.'
 ! go list -m github.com/russross/blackfriday@patch
 stderr '^go: github.com/russross/blackfriday@patch: can''t query version "patch" of module github.com/russross/blackfriday: no existing version is required$'
 
+
 # If we're fetching directly from version control, ignored +incompatible
 # versions should also be omitted by 'go list'.
 
@@ -38,10 +39,23 @@ stderr '^go: github.com/russross/blackfriday@patch: can''t query version "patch"
 [!git] stop
 env GOPROXY=direct
 
-go list -versions -m github.com/russross/blackfriday github.com/russross/blackfriday
+go list -versions -m github.com/russross/blackfriday
 stdout '^github.com/russross/blackfriday v1\.5\.1 v1\.5\.2' # and possibly others
 ! stdout ' v2\.'
 
+# For this module, v2.1.0 exists and has a go.mod file.
+# 'go list -m github.com/russross/[email protected]' will check
+# the latest v2.0 tag, discover that it isn't the right module, and stop there
+# (instead of spending the time to check O(N) previous tags).
+
+! go list -m github.com/russross/[email protected]
+stderr '^go: module github.com/russross/blackfriday: no matching versions for query "v2\.0\"'
+
+# (But asking for exactly v2.0.0+incompatible should still succeed.)
+go list -m github.com/russross/[email protected]+incompatible
+stdout '^github.com/russross/blackfriday v2\.0\.0\+incompatible$'
+
+
 # However, if the latest compatible version does not include a go.mod file,
 # +incompatible versions should still be listed, as they may still reflect the
 # intent of the module author.

src/cmd/go/testdata/script/mod_sumdb_file_path.txt

@@ -1,7 +1,9 @@
 [!net:proxy.golang.org] skip
+[!net:sum.golang.org] skip
 
 env GO111MODULE=on
-env GOSUMDB=
+[go-builder] env GOSUMDB=
+[!go-builder] env GOSUMDB=sum.golang.org # Set explicitly in case GOROOT/go.env is modified.
 env GOPATH=$WORK/gopath1
 
 # With a file-based proxy with an empty checksum directory,

src/cmd/go/testdata/script/mod_sumdb_golang.txt

@@ -1,13 +1,13 @@
 # Test default GOPROXY and GOSUMDB
-env GOPROXY=
-env GOSUMDB=
-go env GOPROXY
-stdout '^https://proxy.golang.org,direct$'
-go env GOSUMDB
-stdout '^sum.golang.org$'
-env GOPROXY=https://proxy.golang.org
-go env GOSUMDB
-stdout '^sum.golang.org$'
+[go-builder] env GOPROXY=
+[go-builder] env GOSUMDB=
+[go-builder] go env GOPROXY
+[go-builder] stdout '^https://proxy.golang.org,direct$'
+[go-builder] go env GOSUMDB
+[go-builder] stdout '^sum.golang.org$'
+[go-builder] env GOPROXY=https://proxy.golang.org
+[go-builder] go env GOSUMDB
+[go-builder] stdout '^sum.golang.org$'
 
 # Download direct from github.
 
@@ -26,8 +26,8 @@ cp go.sum saved.sum
 # files not listed in go.sum.
 
 go clean -modcache
-env GOSUMDB=
-env GOPROXY=
+env GOSUMDB=sum.golang.org
+env GOPROXY=https://proxy.golang.org,direct
 
 go list -x -m all # Download go.mod files.
 ! stderr github