diff --git a/src/cmd/go/mod_test.go b/src/cmd/go/mod_test.go
index 0199559fd2..7c582633e4 100644
--- a/src/cmd/go/mod_test.go
+++ b/src/cmd/go/mod_test.go
@@ -69,83 +69,6 @@ func (tg *testgoData) extract(file string) {
 	}
 }
 
-func TestModGO111MODULE(t *testing.T) {
-	tg := testGoModules(t)
-	defer tg.cleanup()
-
-	tg.tempFile("gp/src/x/y/z/go.mod", "module x/y/z")
-	tg.tempFile("gp/src/x/y/z/w/w.txt", "")
-	tg.tempFile("gp/foo/go.mod", "module example.com/mod")
-	tg.tempFile("gp/foo/bar/baz/quux.txt", "")
-	tg.tempFile("gp/bar/x.txt", "")
-	tg.setenv("GOPATH", tg.path("gp"))
-
-	// In GOPATH/src with go.mod.
-	tg.cd(tg.path("gp/src/x/y/z"))
-	tg.setenv("GO111MODULE", "auto")
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-
-	tg.cd(tg.path("gp/src/x/y/z/w"))
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-
-	tg.setenv("GO111MODULE", "off")
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-
-	tg.setenv("GO111MODULE", "on")
-	tg.run("env", "GOMOD")
-	tg.grepStdout(`.*z[/\\]go.mod$`, "expected module mode enabled")
-
-	// In GOPATH/src without go.mod.
-	tg.cd(tg.path("gp/src/x/y"))
-	tg.setenv("GO111MODULE", "auto")
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-
-	tg.setenv("GO111MODULE", "off")
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-
-	tg.setenv("GO111MODULE", "on")
-	tg.runFail("env", "GOMOD")
-	tg.grepStderr(`cannot find main module root`, "expected module mode failure")
-
-	// Outside GOPATH/src with go.mod.
-	tg.cd(tg.path("gp/foo"))
-	tg.setenv("GO111MODULE", "auto")
-	tg.run("env", "GOMOD")
-	tg.grepStdout(`.*foo[/\\]go.mod$`, "expected module mode enabled")
-
-	tg.cd(tg.path("gp/foo/bar/baz"))
-	tg.run("env", "GOMOD")
-	tg.grepStdout(`.*foo[/\\]go.mod$`, "expected module mode enabled")
-
-	tg.setenv("GO111MODULE", "off")
-	tg.run("env", "GOMOD")
-	tg.grepStdoutNot(`go.mod`, "expected module mode disabled")
-}
-
-func TestModVersionsInGOPATHMode(t *testing.T) {
-	tg := testgo(t)
-	tg.setenv("GO111MODULE", "off") // GOPATH mode
-	defer tg.cleanup()
-	tg.makeTempdir()
-
-	tg.runFail("get", "rsc.io/quote@v1.5.1")
-	tg.grepStderr(`go: cannot use path@version syntax in GOPATH mode`, "expected path@version error")
-
-	tg.runFail("build", "rsc.io/quote@v1.5.1")
-	tg.grepStderr(`can't load package:.* cannot use path@version syntax in GOPATH mode`, "expected path@version error")
-
-	tg.setenv("GO111MODULE", "on") // GOPATH mode
-	tg.tempFile("x/go.mod", "module x")
-	tg.cd(tg.path("x"))
-	tg.runFail("build", "rsc.io/quote@v1.5.1")
-	tg.grepStderr(`can't load package:.* can only use path@version syntax with 'go get'`, "expected path@version error")
-}
-
 func TestModFindModuleRoot(t *testing.T) {
 	tg := testGoModules(t)
 	defer tg.cleanup()
@@ -328,16 +251,6 @@ func TestModFindModulePath(t *testing.T) {
 	// }
 }
 
-func TestModImportModFails(t *testing.T) {
-	tg := testGoModules(t)
-	defer tg.cleanup()
-
-	tg.setenv("GO111MODULE", "off")
-	tg.tempFile("gopath/src/mod/foo/foo.go", "package foo")
-	tg.runFail("list", "mod/foo")
-	tg.grepStderr(`disallowed import path`, "expected disallowed because of module cache")
-}
-
 func TestModEdit(t *testing.T) {
 	// Test that local replacements work
 	// and that they can use a dummy name
@@ -502,91 +415,6 @@ require x.3 v1.99.0
 `)
 }
 
-func TestModLocalModule(t *testing.T) {
-	// Test that local replacements work
-	// and that they can use a dummy name
-	// that isn't resolvable and need not even
-	// include a dot. See golang.org/issue/24100.
-	tg := testGoModules(t)
-	defer tg.cleanup()
-
-	tg.must(os.MkdirAll(tg.path("x/y"), 0777))
-	tg.must(os.MkdirAll(tg.path("x/z"), 0777))
-	tg.must(ioutil.WriteFile(tg.path("x/y/go.mod"), []byte(`
-		module x/y
-		require zz v1.0.0
-		replace zz v1.0.0 => ../z
-	`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y/y.go"), []byte(`package y; import _ "zz"`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/z/go.mod"), []byte(`
-		module x/z
-	`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/z/z.go"), []byte(`package z`), 0666))
-	tg.cd(tg.path("x/y"))
-	tg.run("build")
-}
-
-func TestModTags(t *testing.T) {
-	// Test that build tags are used. See golang.org/issue/24053.
-	tg := testGoModules(t)
-	defer tg.cleanup()
-
-	tg.must(os.MkdirAll(tg.path("x"), 0777))
-	tg.must(ioutil.WriteFile(tg.path("x/go.mod"), []byte(`
-		module x
-	`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/x.go"), []byte(`// +build tag1
-
-		package y
-	`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y.go"), []byte(`// +build tag2
-
-		package y
-	`), 0666))
-	tg.cd(tg.path("x"))
-
-	tg.runFail("list", "-f={{.GoFiles}}")
-	tg.grepStderr("build constraints exclude all Go files", "no Go source files without tags")
-
-	tg.run("list", "-f={{.GoFiles}}", "-tags=tag1")
-	tg.grepStdout(`\[x.go\]`, "Go source files for tag1")
-
-	tg.run("list", "-f={{.GoFiles}}", "-tags", "tag2")
-	tg.grepStdout(`\[y.go\]`, "Go source files for tag2")
-
-	tg.run("list", "-f={{.GoFiles}}", "-tags", "tag1 tag2")
-	tg.grepStdout(`\[x.go y.go\]`, "Go source files for tag1 and tag2")
-}
-
-func TestModFSPatterns(t *testing.T) {
-	tg := testGoModules(t)
-	defer tg.cleanup()
-
-	tg.must(os.MkdirAll(tg.path("x/vendor/v"), 0777))
-	tg.must(os.MkdirAll(tg.path("x/y/z/w"), 0777))
-	tg.must(ioutil.WriteFile(tg.path("x/go.mod"), []byte(`
-		module m
-	`), 0666))
-
-	tg.must(ioutil.WriteFile(tg.path("x/x.go"), []byte(`package x`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/vendor/v/v.go"), []byte(`package v; import "golang.org/x/crypto"`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/vendor/v.go"), []byte(`package main`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y/y.go"), []byte(`package y`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y/z/go.mod"), []byte(`syntax error`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y/z/z.go"), []byte(`package z`), 0666))
-	tg.must(ioutil.WriteFile(tg.path("x/y/z/w/w.go"), []byte(`package w`), 0666))
-
-	tg.cd(tg.path("x"))
-	for _, pattern := range []string{"all", "m/...", "./..."} {
-		tg.run("list", pattern)
-		tg.grepStdout(`^m$`, "expected m")
-		tg.grepStdout(`^m/vendor$`, "must see package named vendor")
-		tg.grepStdoutNot(`vendor/`, "must not see vendored packages")
-		tg.grepStdout(`^m/y$`, "expected m/y")
-		tg.grepStdoutNot(`^m/y/z`, "should ignore submodule m/y/z...")
-	}
-}
-
 func TestModGetVersions(t *testing.T) {
 	tg := testGoModules(t)
 	defer tg.cleanup()
diff --git a/src/cmd/go/script_test.go b/src/cmd/go/script_test.go
index 0d8c5921bf..78bb1cb50e 100644
--- a/src/cmd/go/script_test.go
+++ b/src/cmd/go/script_test.go
@@ -73,6 +73,7 @@ type testScript struct {
 
 // setup sets up the test execution temporary directory and environment.
 func (ts *testScript) setup() {
+	StartProxy()
 	ts.workdir = filepath.Join(testTmpDir, "script-"+ts.name)
 	ts.check(os.MkdirAll(filepath.Join(ts.workdir, "tmp"), 0777))
 	ts.check(os.MkdirAll(filepath.Join(ts.workdir, "gopath/src"), 0777))
@@ -85,6 +86,7 @@ func (ts *testScript) setup() {
 		"GOCACHE=" + testGOCACHE,
 		"GOOS=" + runtime.GOOS,
 		"GOPATH=" + filepath.Join(ts.workdir, "gopath"),
+		"GOPROXY=" + proxyURL,
 		"GOROOT=" + testGOROOT,
 		tempEnvName() + "=" + filepath.Join(ts.workdir, "tmp"),
 		"devnull=" + os.DevNull,
@@ -604,7 +606,7 @@ func (ts *testScript) parse(line string) []string {
 		quoted = false // currently processing quoted text
 	)
 	for i := 0; ; i++ {
-		if !quoted && (i >= len(line) || line[i] == ' ' || line[i] == '\t' || line[i] == '\r') {
+		if !quoted && (i >= len(line) || line[i] == ' ' || line[i] == '\t' || line[i] == '\r' || line[i] == '#') {
 			// Found arg-separating space.
 			if start >= 0 {
 				arg += ts.expand(line[start:i])
@@ -612,7 +614,7 @@ func (ts *testScript) parse(line string) []string {
 				start = -1
 				arg = ""
 			}
-			if i >= len(line) {
+			if i >= len(line) || line[i] == '#' {
 				break
 			}
 			continue
diff --git a/src/cmd/go/testdata/script/README b/src/cmd/go/testdata/script/README
index 4334ed32a6..55bc48b215 100644
--- a/src/cmd/go/testdata/script/README
+++ b/src/cmd/go/testdata/script/README
@@ -30,6 +30,7 @@ Scripts also have access to these other environment variables:
 	GOCACHE=<actual GOCACHE being used outside the test>
 	GOOS=<target GOOS>
 	GOPATH=$WORK/gopath
+	GOPROXY=<local module proxy serving from cmd/go/testdata/mod>
 	GOROOT=<actual GOROOT>
 	HOME=/no-home
 	PATH=<actual PATH>
@@ -48,10 +49,11 @@ by a tiny script engine in ../../script_test.go (not the system shell).
 The script stops and the overall test fails if any particular command fails.
 
 Each line is parsed into a sequence of space-separated command words,
-with environment variable expansion. Adding single quotes around text
-keeps spaces in that text from being treated as word separators and also
-disables environment variable expansion. Inside a single-quoted block of
-text, a repeated single quote indicates a literal single quote, as in:
+with environment variable expansion and # marking an end-of-line comment.
+Adding single quotes around text keeps spaces in that text from being treated
+as word separators and also disables environment variable expansion.
+Inside a single-quoted block of text, a repeated single quote indicates
+a literal single quote, as in:
 
 	'Don''t communicate by sharing memory.'
 
diff --git a/src/cmd/go/testdata/script/mod_build_tags.txt b/src/cmd/go/testdata/script/mod_build_tags.txt
new file mode 100644
index 0000000000..1347eaacbf
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_build_tags.txt
@@ -0,0 +1,30 @@
+# Test that build tags are used.
+# golang.org/issue/24053.
+
+env GO111MODULE=on
+
+cd x
+! go list -f {{.GoFiles}}
+stderr 'build constraints exclude all Go files'
+
+go list -f {{.GoFiles}} -tags tag1
+stdout '\[x.go\]'
+
+go list -f {{.GoFiles}} -tags tag2
+stdout '\[y\.go\]'
+
+go list -f {{.GoFiles}} -tags 'tag1 tag2'
+stdout '\[x\.go y\.go\]'
+
+-- x/go.mod --
+module x
+
+-- x/x.go --
+// +build tag1
+
+package y
+
+-- x/y.go --
+// +build tag2
+
+package y
diff --git a/src/cmd/go/testdata/script/mod_enabled.txt b/src/cmd/go/testdata/script/mod_enabled.txt
new file mode 100644
index 0000000000..189d4edc91
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_enabled.txt
@@ -0,0 +1,67 @@
+# GO111MODULE=auto should only trigger outside GOPATH/src
+env GO111MODULE=auto
+
+cd $GOPATH/src/x/y/z
+go env GOMOD
+! stdout . # no non-empty lines
+
+cd $GOPATH/src/x/y/z/w
+go env GOMOD
+! stdout .
+
+cd $GOPATH/src/x/y
+go env GOMOD
+! stdout .
+
+cd $GOPATH/foo
+go env GOMOD
+stdout foo[/\\]go.mod
+
+cd $GOPATH/foo/bar/baz
+go env GOMOD
+stdout foo[/\\]go.mod
+
+# GO111MODULE=on should trigger everywhere
+env GO111MODULE=on
+
+cd $GOPATH/src/x/y/z
+go env GOMOD
+stdout z[/\\]go.mod
+
+cd $GOPATH/src/x/y/z/w
+go env GOMOD
+stdout z[/\\]go.mod
+
+cd $GOPATH/src/x/y
+! go env GOMOD
+stderr 'cannot find main module root'
+
+cd $GOPATH/foo
+go env GOMOD
+stdout foo[/\\]go.mod
+
+cd $GOPATH/foo/bar/baz
+go env GOMOD
+stdout foo[/\\]go.mod
+
+# GO111MODULE=off should trigger nowhere
+env GO111MODULE=off
+
+cd $GOPATH/src/x/y/z
+go env GOMOD
+! stdout .+
+
+cd $GOPATH/foo
+go env GOMOD
+! stdout .+
+
+cd $GOPATH/foo/bar/baz
+go env GOMOD
+! stdout .+
+
+-- $GOPATH/src/x/y/z/go.mod --
+module x/y/z
+-- $GOPATH/src/x/y/z/w/w.txt --
+-- $GOPATH/foo/go.mod --
+module example.com/mod
+-- $GOPATH/foo/bar/baz/quux.txt --
diff --git a/src/cmd/go/testdata/script/mod_fs_patterns.txt b/src/cmd/go/testdata/script/mod_fs_patterns.txt
new file mode 100644
index 0000000000..b5350c3eed
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_fs_patterns.txt
@@ -0,0 +1,54 @@
+# File system pattern searches should skip sub-modules and vendor directories.
+
+env GO111MODULE=on
+
+cd x
+
+# all packages
+go list all
+stdout ^m$
+stdout ^m/vendor$
+! stdout vendor/
+stdout ^m/y$
+! stdout ^m/y/z
+
+# path pattern
+go list m/...
+stdout ^m$
+stdout ^m/vendor$
+! stdout vendor/
+stdout ^m/y$
+! stdout ^m/y/z
+
+# directory pattern
+go list ./...
+stdout ^m$
+stdout ^m/vendor$
+! stdout vendor/
+stdout ^m/y$
+! stdout ^m/y/z
+
+-- x/go.mod --
+module m
+
+-- x/x.go --
+package x
+
+-- x/vendor/v/v.go --
+package v
+import _ "golang.org/x/crypto"
+
+-- x/vendor/v.go --
+package main
+
+-- x/y/y.go --
+package y
+
+-- x/y/z/go.mod --
+syntax error!
+
+-- x/y/z/z.go --
+package z
+
+-- x/y/z/w/w.go --
+package w
diff --git a/src/cmd/go/testdata/script/mod_import_mod.txt b/src/cmd/go/testdata/script/mod_import_mod.txt
new file mode 100644
index 0000000000..46f45c7109
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_import_mod.txt
@@ -0,0 +1,7 @@
+# Test that GOPATH/src/mod is excluded
+env GO111MODULE=off
+! go list mod/foo
+stderr 'disallowed import path'
+
+-- mod/foo/foo.go --
+package foo
diff --git a/src/cmd/go/testdata/script/mod_local_replace.txt b/src/cmd/go/testdata/script/mod_local_replace.txt
new file mode 100644
index 0000000000..19bc8f3904
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_local_replace.txt
@@ -0,0 +1,23 @@
+# Test that local replacements work even with dummy module names.
+# golang.org/issue/24100.
+
+env GO111MODULE=on
+
+cd x/y
+go list -f '{{.Dir}}' zz
+stdout x[/\\]z$
+
+-- x/y/go.mod --
+module x/y
+require zz v1.0.0
+replace zz v1.0.0 => ../z
+
+-- x/y/y.go --
+package y
+import _ "zz"
+
+-- x/z/go.mod --
+module x/z
+
+-- x/z/z.go --
+package z
diff --git a/src/cmd/go/testdata/script/mod_versions.txt b/src/cmd/go/testdata/script/mod_versions.txt
new file mode 100644
index 0000000000..fd5e5c589d
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_versions.txt
@@ -0,0 +1,14 @@
+# Test rejection of pkg@version in GOPATH mode.
+env GO111MODULE=off
+! go get rsc.io/quote@v1.5.1
+stderr 'cannot use path@version syntax in GOPATH mode'
+! go build rsc.io/quote@v1.5.1
+stderr 'cannot use path@version syntax in GOPATH mode'
+
+env GO111MODULE=on
+cd x
+! go build rsc.io/quote@v1.5.1
+stderr 'can only use path@version syntax with ''go get'''
+
+-- x/go.mod --
+module x