Handle multi line option and argument description in the generated he…

…lp message (#96)

The help output will resemble:

```
Usage: app [-o] ARG

Longer App Desc

Arguments:
  ARG           Argument
                Description
                Multiple
                Lines

Options:
  -o, --opt     Option
                does something
                another line (env $XXX_TEST) (default "default")
  -f, --force   Force
                does something
                another line (env $YYY_TEST)
```

cli_test.go

@@ -887,6 +887,36 @@ func TestLongHelpMessage(t *testing.T) {
  require.Equal(t, expected, []byte(err))
 }
 
+func TestMultiLineDescInHelpMessage(t *testing.T) {
+ var out, err string
+ defer captureAndRestoreOutput(&out, &err)()
+
+ exitCalled := false
+ defer exitShouldBeCalledWith(t, 0, &exitCalled)()
+
+ app := App("app", "App Desc")
+ app.LongDesc = "Longer App Desc"
+ app.Spec = "[-o] ARG"
+
+ app.String(StringOpt{Name: "o opt", Value: "default", EnvVar: "XXX_TEST", Desc: "Option\ndoes something\n another line"})
+ app.Bool(BoolOpt{Name: "f force", Value: false, EnvVar: "YYY_TEST", Desc: "Force\ndoes something\n another line"})
+ app.String(StringArg{Name: "ARG", Value: "", Desc: "Argument\nDescription\nMultiple\nLines"})
+
+ app.Action = func() {}
+ require.NoError(t,
+ app.Run([]string{"app", "-h"}))
+
+ if *genGolden {
+ require.NoError(t,
+ ioutil.WriteFile("testdata/multi-line-desc-help-output.txt.golden", []byte(err), 0644))
+ }
+
+ expected, e := ioutil.ReadFile("testdata/multi-line-desc-help-output.txt")
+ require.NoError(t, e, "Failed to read the expected help output from testdata/long-help-output.txt")
+
+ require.Equal(t, expected, []byte(err))
+}
+
 func TestVersionShortcut(t *testing.T) {
  defer suppressOutput()()
  exitCalled := false

commands.go

@@ -3,6 +3,7 @@ package cli
 import (
  "flag"
  "fmt"
+ "io"
  "strings"
  "text/tabwriter"
 
@@ -545,7 +546,7 @@ func (c *Cmd) printHelp(longDesc bool) {
  env = formatEnvVarsForHelp(arg.EnvVar)
  value = formatValueForHelp(arg.HideValue, arg.Value)
  )
- fmt.Fprintf(w, " %s\t%s\n", arg.Name, joinStrings(arg.Desc, env, value))
+ printTabbedRow(w, arg.Name, joinStrings(arg.Desc, env, value))
  }
  }
 
@@ -558,7 +559,7 @@ func (c *Cmd) printHelp(longDesc bool) {
  env = formatEnvVarsForHelp(opt.EnvVar)
  value = formatValueForHelp(opt.HideValue, opt.Value)
  )
- fmt.Fprintf(w, " %s\t%s\n", optNames, joinStrings(opt.Desc, env, value))
+ printTabbedRow(w, optNames, joinStrings(opt.Desc, env, value))
  }
  }
 
@@ -765,3 +766,16 @@ func joinStrings(parts ...string) string {
  }
  return res
 }
+
+func printTabbedRow(w io.Writer, s1 string, s2 string) {
+ lines := strings.Split(s2, "\n")
+ fmt.Fprintf(w, " %s\t%s\n", s1, strings.TrimSpace(lines[0]))
+
+ if len(lines) == 1 {
+ return
+ }
+
+ for _, line := range lines[1:] {
+ fmt.Fprintf(w, " %s\t%s\n", "", strings.TrimSpace(line))
+ }
+}

commands_test.go

@@ -1379,3 +1379,27 @@ func TestJoinStrings(t *testing.T) {
  })
  }
 }
+
+func TestPrintTabbedRow(t *testing.T) {
+ cases := []struct {
+ s1, s2 string
+ expected string
+ }{
+ {"", "", " \t\n"},
+ {"a", "", " a\t\n"},
+ {"a", "b", " a\tb\n"},
+ {"a", " b", " a\tb\n"},
+ {"a", "b\n", " a\tb\n \t\n"},
+ {"a", "b\nc", " a\tb\n \tc\n"},
+ }
+
+ for _, cas := range cases {
+ t.Run(fmt.Sprintf("%q, %q", cas.s1, cas.s2), func(t *testing.T) {
+ t.Logf("Testing %q, %q", cas.s1, cas.s2)
+ var out strings.Builder
+ printTabbedRow(&out, cas.s1, cas.s2)
+
+ require.Equal(t, cas.expected, out.String())
+ })
+ }
+}

testdata/multi-line-desc-help-output.txt

@@ -0,0 +1,18 @@
+
+Usage: app [-o] ARG
+
+Longer App Desc
+
+Arguments: 
+ ARG Argument
+ Description
+ Multiple
+ Lines
+
+Options: 
+ -o, --opt Option
+ does something
+ another line (env $XXX_TEST) (default "default")
+ -f, --force Force
+ does something
+ another line (env $YYY_TEST)