CLI test coverage

internal/testingutil/testingutil.go

@@ -0,0 +1,43 @@
+package testingutil
+
+import (
+	"os"
+	"testing"
+)
+
+// MustReadFile reads all data from filename. Fail on error.
+func MustReadFile(tb testing.TB, filename string) []byte {
+	tb.Helper()
+	b, err := os.ReadFile(filename)
+	if err != nil {
+		tb.Fatal(err)
+	}
+	return b
+}
+
+// Getpwd returns the working directory. Fail on error.
+func Getwd(tb testing.TB) string {
+	tb.Helper()
+
+	dir, err := os.Getwd()
+	if err != nil {
+		tb.Fatal(err)
+	}
+	return dir
+}
+
+// Setenv sets the environment variable key to value. The returned function reverts it.
+func Setenv(tb testing.TB, key, value string) func() {
+	tb.Helper()
+
+	prevValue := os.Getenv(key)
+	if err := os.Setenv(key, value); err != nil {
+		tb.Fatal(err)
+	}
+
+	return func() {
+		if err := os.Setenv(key, prevValue); err != nil {
+			tb.Fatal(tb)
+		}
+	}
+}