Merge pull request #140 from antichris/gocomplete-suppress-errors

gocomplete: suppress error output by default

gocomplete/complete.go

@@ -2,10 +2,17 @@
 package main
 
 import (
+	"io/ioutil"
+	"log"
+	"os"
+
 	"github.com/posener/complete/v2"
 	"github.com/posener/complete/v2/predict"
 )
 
+// envVerbose is the sys env var that controls error output verbosity.
+const envVerbose = "GOCOMP_VERBOSE"
+
 var (
 	ellipsis   = predict.Set{"./..."}
 	anyPackage = complete.PredictFunc(predictPackages)
@@ -15,6 +22,10 @@ var (
 )
 
 func main() {
+	if os.Getenv(envVerbose) != "1" {
+		log.SetOutput(ioutil.Discard)
+	}
+
 	build := &complete.Command{
 		Flags: map[string]complete.Predictor{
 			"o": anyFile,

gocomplete/tests_test.go

@@ -1,8 +1,14 @@
 package main
 
 import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
 	"os"
 	"sort"
+	"strconv"
+	"strings"
 	"testing"
 
 	"bou.ke/monkey"
@@ -21,7 +27,11 @@ func TestPredictions(t *testing.T) {
 		{
 			name:      "predict tests ok",
 			predictor: predictTest,
-			want:      []string{"TestPredictions", "Example"},
+			want: []string{
+				"TestPredictions",
+				"Example",
+				"TestErrorSupression",
+			},
 		},
 		{
 			name:      "predict benchmark ok",
@@ -64,3 +74,71 @@ func equal(s1, s2 []string) bool {
 	}
 	return true
 }
+
+func TestErrorSupression(t *testing.T) {
+	defer monkey.Patch(os.Exit, func(int) {}).Unpatch()
+
+	// Completion API environment variable names.
+	const envLine, envPoint = "COMP_LINE", "COMP_POINT"
+
+	// line should work out to
+	//
+	// * on most POSIX:
+	//     go test /tmp/
+	// * on MacOS X:
+	//     go test /var/folders/<randomized_pathname>/T//
+	// * on Windows:
+	//     go test C:\Users\<username>\AppData\Local\Temp\
+	//
+	// which should trigger "failed importing directory: ... no
+	// buildable Go source files..." error messages.
+	var line = "go test " + os.TempDir() + string(os.PathSeparator)
+
+	defer os.Unsetenv(envLine)
+	defer os.Unsetenv(envPoint)
+	os.Setenv(envLine, line)
+	os.Setenv(envPoint, strconv.Itoa(len(line)))
+
+	tests := []struct {
+		verbose string
+		wantErr bool
+	}{{
+		verbose: "",
+		wantErr: false,
+	}, {
+		verbose: "1",
+		wantErr: true,
+	}}
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf(
+			"%s=%q", envVerbose, tt.verbose,
+		), func(t *testing.T) {
+			// Discard completion (stdout).
+			r, w, err := os.Pipe()
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer w.Close()
+			defer func(o *os.File) { os.Stdout = o }(os.Stdout)
+			os.Stdout = w
+			go io.Copy(ioutil.Discard, r)
+
+			// "Redirect" stderr into a buffer.
+			b := &strings.Builder{}
+			log.SetOutput(b)
+
+			defer os.Unsetenv(envVerbose)
+			os.Setenv(envVerbose, tt.verbose)
+
+			main()
+
+			gotErr := b.Len() != 0
+			if tt.wantErr && !gotErr {
+				t.Fatal("want something in stderr, got nothing")
+			} else if !tt.wantErr && gotErr {
+				t.Fatalf("want nothing in stderr, got %d bytes",
+					b.Len())
+			}
+		})
+	}
+}