ffcli: DefaultUsageText: print valid defaults for bool flags (#79)

* ffcli: DefaultUsageText: print valid defaults for bool flags

* ffcli: fix test for new DefaultUsageFunc output

ffcli/command.go

@@ -226,20 +226,33 @@ func DefaultUsageFunc(c *Command) string {
 		fmt.Fprintf(&b, "FLAGS\n")
 		tw := tabwriter.NewWriter(&b, 0, 2, 2, ' ', 0)
 		c.FlagSet.VisitAll(func(f *flag.Flag) {
+			space := " "
+			if isBoolFlag(f) {
+				space = "="
+			}
+
 			def := f.DefValue
 			if def == "" {
 				def = "..."
 			}
-			fmt.Fprintf(tw, "  -%s %s\t%s\n", f.Name, def, f.Usage)
+
+			fmt.Fprintf(tw, "  -%s%s%s\t%s\n", f.Name, space, def, f.Usage)
 		})
 		tw.Flush()
 		fmt.Fprintf(&b, "\n")
 	}
 
-	return strings.TrimSpace(b.String())
+	return strings.TrimSpace(b.String()) + "\n"
 }
 
 func countFlags(fs *flag.FlagSet) (n int) {
 	fs.VisitAll(func(*flag.Flag) { n++ })
 	return n
 }
+
+func isBoolFlag(f *flag.Flag) bool {
+	b, ok := f.Value.(interface {
+		IsBoolFlag() bool
+	})
+	return ok && b.IsBoolFlag()
+}

ffcli/command_test.go

@@ -197,7 +197,7 @@ func TestHelpUsage(t *testing.T) {
 
 			err := command.ParseAndRun(context.Background(), testcase.args)
 			assertErrorIs(t, flag.ErrHelp, err)
-			assertString(t, testcase.output, buf.String())
+			assertMultilineString(t, testcase.output, buf.String())
 		})
 	}
 }
@@ -512,10 +512,10 @@ func assertErrorIs(t *testing.T, want, have error) {
 	}
 }
 
-func assertString(t *testing.T, want, have string) {
+func assertMultilineString(t *testing.T, want, have string) {
 	t.Helper()
 	if want != have {
-		t.Fatalf("want %q, have %q", want, have)
+		t.Fatalf("\nwant:\n%s\n\nhave:\n%s\n", want, have)
 	}
 }
 
@@ -543,10 +543,10 @@ USAGE
 Some long help.
 
 FLAGS
-  -b false  bool
+  -b=false  bool
   -d 0s     time.Duration
   -f 0      float64
   -i 0      int
   -s ...    string
   -x ...    collection of strings (repeatable)
-`) + "\n"
+`) + "\n\n"