modules support: adjust wording based on first-pass review, and updat…

…e vendor test (#3)

* travis: attempt to install cmd/testscript

* testing: initial check of 'go-fuzz-build -h' output to see if any testscripts work

* testing: change name of first test script

* travis: check if the 'testscript' cmd seems to function at all.

* testing: use the exec command to invoke 'go-fuzz-build -h'

* testing: create initially failing test case for v2 modules

* travis: run testscript for v2 modules

* testing: remember to use 'exec' to invoke go-fuzz-build

* testing: adjust comments in v2 module testscript

* go-fuzz-build: preliminary module support

* testing: flip  from an expected failure to an expected pass for a module test

* go-fuzz-build: update comments for preliminary modules support

* go-fuzz: preliminary modules support for go-fuzz itself

* travis: go-fuzz-defs sanity check

* travis: additional temp sanity check

* travis: add more comments, some additional sanity checks in case we need to debug in future

* travis: s/go-fuzz-deps/go-fuzz-dep/

* testing: validate behavior of v2 modules

* testing: renamed fuzz_help.txt

* testing: update travis to use the renamed testscripts

* travis: conditionally set GO111MODULE=auto, and test Go 1.13 rather than 1.11

* testing: validate modules outside GOPATH

* testing: validate modules inside GOPATH

* testing: invoke timeout properly

* testing: preliminary test for vendored modules (not yet supported)

* testing: validate how go-fuzz-dep and go-fuzz-defs are found

* travis: run the latest testscripts for modules testing

* testing: fix typo in mod_outside_gopath.txt file name

* travis: fix typo in file name

* go-fuzz-build: detect -mod=vendor

* testing: validate we get a proper error for -mod=vendor

* readme: describe preliminary modules support

* readme: correct typo in modules support

* readme: adjust modules support section

* readme: tweak wording based on PR review

* go-fuzz: tweak comment wording by removing "preliminary modules support"

* go-fuzz-build: tweak comment wording by removing "preliminary modules support"

* mod_vendor.txt: avoid triggering Go 1.14 auto detection of a vendor directory

README.md

@@ -144,12 +144,12 @@ You must have a `require` directive for `github.com/dvyukov/go-fuzz` in your go.
 
 1. Prior to invoking go-fuzz-build, add a `require` for `github.com/dvyukov/go-fuzz` in your go.mod. A common approach for tracking tool dependencies like this is [via a tools.go file](https://github.com/golang/go/wiki/Modules#how-can-i-track-tool-dependencies-for-a-module). Alternatively, you could for example manually add `require github.com/dvyukov/go-fuzz latest` to your go.mod.
 
-2. If you do not have a `require` for `github.com/dvyukov/go-fuzz` in your go.mod, go-fuzz-build will add one automatically. If desired, you can revert your go.mod file when you are done.
+2. If you do not have a `require` for `github.com/dvyukov/go-fuzz` in your go.mod, go-fuzz-build will add one automatically. If desired, you can revert your go.mod file when go-fuzz-build is done.
 
 Vendoring with modules is not yet supported. A `vendor` directory will be ignored, and go-fuzz will report an error if `GOFLAGS=-mod=vendor` is set.
 
 Note that while modules are used to prepare the build, the final instrumented build is still done in GOPATH mode.
-For most code, this should not matter.
+For most modules, this should not matter.
 
 ## libFuzzer support
 

go-fuzz-build/main.go

@@ -61,10 +61,9 @@ func makeTags() string {
 func basePackagesConfig() *packages.Config {
 	cfg := new(packages.Config)
 
-	// Preliminary modules support: note that we do not set 
-	// GO111MODULE here in order to respect any GO111MODULE setting by the user
-	// as we are finding dependencies. Note, however, that we are
-	// still setting up a GOPATH to build, so we later will force 
+	// Note that we do not set GO111MODULE here in order to respect any GO111MODULE
+	// setting by the user as we are finding dependencies. Note, however, that 
+	// we are still setting up a GOPATH to build, so we later will force 
 	// GO111MODULE to be off when building so that we are in GOPATH mode.
 	// If the user has not set GO111MODULE, the meaning here is
 	// left up to cmd/go (defaulting to 'auto' in Go 1.11-1.13,
@@ -109,7 +108,7 @@ func main() {
 		c.failf("-race and -libfuzzer are incompatible")
 	}
 	if checkModVendor() {
-		// Preliminary modules support: we don't support -mod=vendor.
+		// We don't support -mod=vendor with modules.
 		// Part of the issue is go-fuzz-dep and go-fuzz-defs
 		// won't be in the user's vendor directory.
 		c.failf("GOFLAGS with -mod=vendor is not supported")
@@ -529,9 +528,8 @@ func (c *Context) buildInstrumentedBinary(blocks *[]CoverBlock, sonar *[]CoverBl
 	args = append(args, "-o", outf, mainPkg)
 	cmd := exec.Command("go", args...)
 
-	// Preliminary modules support: we are constructing a GOPATH
-	// environment, so while building we force GOPATH mode here
-	// via GO111MODULE=off.
+	// We are constructing a GOPATH environment, so while building
+	// we force GOPATH mode here via GO111MODULE=off.
 	cmd.Env = append(os.Environ(),
 		"GOROOT="+filepath.Join(c.workdir, "goroot"),
 		"GOPATH="+filepath.Join(c.workdir, "gopath"),

go-fuzz/main.go

@@ -100,9 +100,8 @@ func main() {
 			// Try the default. Best effort only.
 			var bin string
 			cfg := new(packages.Config)
-			// Preliminary modules support: note that we do not set 
-			// GO111MODULE here in order to respect any GO111MODULE setting by the user
-			// as we are finding dependencies. See preliminary modules support 
+			// Note that we do not set GO111MODULE here in order to respect any GO111MODULE 
+			// setting by the user as we are finding dependencies. See modules support 
 			// comments in go-fuzz-build/main.go for more details.
 			cfg.Env = os.Environ()
 			pkgs, err := packages.Load(cfg, ".")

testscripts/mod_vendor.txt

@@ -92,6 +92,8 @@ rm foo-fuzz.zip
 # foo has vendored bar and (in theory) made a code change inside foo's vendor 
 # directory. The bar code inside foo's vendor compiles, but the original
 # bar code does not compile.
+# The go.mod files set 'go 1.13' to avoid triggering the Go 1.14 auto
+# detection of a vendor directory.
 
 -- foo/fuzz.go --
 package foo
@@ -106,6 +108,8 @@ func FuzzUsingVendor(data []byte) int {
 -- foo/go.mod --
 module example.com/foo
 
+go 1.13
+
 require (
     example.com/bar v0.0.0
     github.com/dvyukov/go-fuzz latest
@@ -131,3 +135,5 @@ func Bar() string {
 
 -- bar/go.mod --
 module example.com/bar
+
+go 1.13