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package flagutil
import (
"flag"
"os"
"testing"
)
func TestSetFlagsFromEnv(t *testing.T) {
fs := flag.NewFlagSet("testing", flag.ExitOnError)
fs.String("a", "", "")
fs.String("b", "", "")
fs.String("c", "", "")
fs.Parse([]string{})
os.Clearenv()
// flags should be settable using env vars
os.Setenv("MYPROJ_A", "foo")
// and command-line flags
if err := fs.Set("b", "bar"); err != nil {
t.Fatal(err)
}
// command-line flags take precedence over env vars
os.Setenv("MYPROJ_C", "woof")
if err := fs.Set("c", "quack"); err != nil {
t.Fatal(err)
}
// first verify that flags are as expected before reading the env
for f, want := range map[string]string{
"a": "",
"b": "bar",
"c": "quack",
} {
if got := fs.Lookup(f).Value.String(); got != want {
t.Fatalf("flag %q=%q, want %q", f, got, want)
}
}
// now read the env and verify flags were updated as expected
err := SetFlagsFromEnv(fs, "MYPROJ")
if err != nil {
t.Errorf("err=%v, want nil", err)
}
for f, want := range map[string]string{
"a": "foo",
"b": "bar",
"c": "quack",
} {
if got := fs.Lookup(f).Value.String(); got != want {
t.Errorf("flag %q=%q, want %q", f, got, want)
}
}
}
func TestSetFlagsFromEnvBad(t *testing.T) {
// now verify that an error is propagated
fs := flag.NewFlagSet("testing", flag.ExitOnError)
fs.Int("x", 0, "")
os.Setenv("MYPROJ_X", "not_a_number")
if err := SetFlagsFromEnv(fs, "MYPROJ"); err == nil {
t.Errorf("err=nil, want != nil")
}
}
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