test: improve golden test error messages

google · Jan 23, 2022 · 4c00359 · 4c00359
1 parent 9aeeaa3
commit 4c00359
Showing 1 changed file with 15 additions and 9 deletions.
diff --git a/e2e_test.go b/e2e_test.go
@@ -15,9 +15,9 @@
 package main_test
 
 import (
+	"bytes"
 	"errors"
 	"flag"
-	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -29,7 +29,7 @@ import (
 
 var update = flag.Bool("update", false, "update golden files")
 
-func TestCsvCmd(t *testing.T) {
+func TestCsvCommandE2E(t *testing.T) {
 	var tests = []struct {
 		workdir string
 	}{
@@ -42,14 +42,14 @@ func TestCsvCmd(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	// This installs go-licenses CLI.
+	// This builds and installs go-licenses CLI to $(go env GOPATH)/bin.
 	cmd := exec.Command("go", "install", ".")
 	_, err = cmd.Output()
 	if err != nil {
 		t.Fatal(err)
 	}
 	for _, tc := range tests {
-		t.Run(fmt.Sprintf("go-licenses csv . in %s", tc.workdir), func(t *testing.T) {
+		t.Run(tc.workdir, func(t *testing.T) {
 			err := os.Chdir(filepath.Join(originalWorkDir, tc.workdir))
 			if err != nil {
 				t.Fatal(err)
@@ -60,12 +60,14 @@ func TestCsvCmd(t *testing.T) {
 				t.Fatalf("downloading go modules:\n%s", string(log))
 			}
 			cmd = exec.Command("go-licenses", "csv", ".")
+			// Capture stderr to buffer.
+			var stderr bytes.Buffer
+			cmd.Stderr = &stderr
+			t.Logf("%s $ go-licenses csv .", tc.workdir)
 			output, err := cmd.Output()
 			if err != nil {
-				if exitErr, ok := err.(*exec.ExitError); ok {
-					t.Fatalf("running go-licenses csv .:\n%s", string(exitErr.Stderr))
-				}
-				t.Fatal(err)
+				t.Logf("\n=== start of log ===\n%s=== end of log ===\n\n\n", stderr.String())
+				t.Fatalf("running go-licenses csv: %s. Full log shown above.", err)
 			}
 			got := string(output)
 			goldenFilePath := "licenses.csv"
@@ -84,7 +86,11 @@ func TestCsvCmd(t *testing.T) {
 			}
 			golden := string(goldenBytes)
 			if got != golden {
-				t.Fatalf("result of go-licenses csv . does not match the golden file. Update the golden by running `go test --update .`. Diff -golden +got:\n%s", cmp.Diff(golden, got))
+				t.Logf("\n=== start of log ===\n%s=== end of log ===\n\n\n", stderr.String())
+				t.Fatalf("result of go-licenses csv does not match the golden file.\n"+
+					"Diff -golden +got:\n%s\n"+
+					"Update the golden by running `go test --update .`",
+					cmp.Diff(golden, got))
 			}
 		})
 	}