Merge pull request github#11832 from github/mbg/fix/go-version-warnings

Go: Handle output from `go version` more gracefully

Author: smowton

go/extractor/cli/go-autobuilder/go-autobuilder.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -56,11 +57,23 @@ func getEnvGoVersion() string {
 		if err != nil {
 			log.Fatalf("Unable to run the go command, is it installed?\nError: %s", err.Error())
 		}
-		goVersion = strings.Fields(string(gover))[2]
+		goVersion = parseGoVersion(string(gover))
 	}
 	return goVersion
 }
 
+// The 'go version' command may output warnings on separate lines before
+// the actual version string is printed. This function parses the output
+// to retrieve just the version string.
+func parseGoVersion(data string) string {
+	var lastLine string
+	sc := bufio.NewScanner(strings.NewReader(data))
+	for sc.Scan() {
+		lastLine = sc.Text()
+	}
+	return strings.Fields(lastLine)[2]
+}
+
 // Returns the current Go version in semver format, e.g. v1.14.4
 func getEnvGoSemVer() string {
 	goVersion := getEnvGoVersion()

go/extractor/cli/go-autobuilder/go-autobuilder_test.go

@@ -20,3 +20,16 @@ func TestGetImportPathFromRepoURL(t *testing.T) {
 		}
 	}
 }
+
+func TestParseGoVersion(t *testing.T) {
+	tests := map[string]string{
+		"go version go1.18.9 linux/amd64": "go1.18.9",
+		"warning: GOPATH set to GOROOT (/usr/local/go) has no effect\ngo version go1.18.9 linux/amd64": "go1.18.9",
+	}
+	for input, expected := range tests {
+		actual := parseGoVersion(input)
+		if actual != expected {
+			t.Errorf("Expected parseGoVersion(\"%s\") to be \"%s\", but got \"%s\".", input, expected, actual)
+		}
+	}
+}