Repository: spf13/cobra
Pull request #163 (2015-09-25 15:10:33)

Improve suggestions
Multiple improvements to suggestions when "unknown command" errors happen. Basically a `HasPrefix` will now also match, and adds the `SuggestFor` attribute to allow explicit suggestions. By setting that attribute you can for example suggest the valid command `remove` when users try `delete`, if for some reason you don't want actual aliases.


Patch:
diff --git a/README.md b/README.md
index 8869ab9..0887e46 100644
--- a/README.md
+++ b/README.md
@@ -442,6 +442,18 @@ or
 
     command.SuggestionsMinimumDistance = 1
 
+You can also explicitly set names for which a given command will be suggested using the `SuggestFor` attribute. This allows suggestions for strings that are not close in terms of string distance, but makes sense in your set of commands and for some which you don't want aliases. Example:
+
+```
+$ hugo delete
+unknown command "delete" for "hugo"
+
+Did you mean this?
+  remove
+
+Run 'hugo --help' for usage.
+```
+
 ## Generating markdown formatted documentation for your command
 
 Cobra can generate a markdown formatted document based on the subcommands, flags, etc. A simple example of how to do this for your command can be found in [Markdown Docs](md_docs.md)
diff --git a/command.go b/command.go
index 0cc0b72..b67e025 100644
--- a/command.go
+++ b/command.go
@@ -39,6 +39,8 @@ type Command struct {
 	Use string
 	// An array of aliases that can be used instead of the first word in Use.
 	Aliases []string
+	// An array of command names for which this command will be suggested - similar to aliases but only suggests.
+	SuggestFor []string
 	// The short description shown in the 'help' output.
 	Short string
 	// The long message shown in the 'help <this-command>' output.
@@ -429,33 +431,44 @@ func (c *Command) Find(args []string) (*Command, []string, error) {
 
 	// root command with subcommands, do subcommand checking
 	if commandFound == c && len(argsWOflags) > 0 {
-		suggestions := ""
+		suggestionsString := ""
 		if !c.DisableSuggestions {
 			if c.SuggestionsMinimumDistance <= 0 {
 				c.SuggestionsMinimumDistance = 2
 			}
-			similar := []string{}
-			for _, cmd := range c.commands {
-				if cmd.IsAvailableCommand() {
-					levenshtein := ld(argsWOflags[0], cmd.Name(), true)
-					if levenshtein <= c.SuggestionsMinimumDistance {
-						similar = append(similar, cmd.Name())
-					}
-				}
-			}
-			if len(similar) > 0 {
-				suggestions += "\n\nDid you mean this?\n"
-				for _, s := range similar {
-					suggestions += fmt.Sprintf("\t%v\n", s)
+			if suggestions := c.SuggestionsFor(argsWOflags[0]); len(suggestions) > 0 {
+				suggestionsString += "\n\nDid you mean this?\n"
+				for _, s := range suggestions {
+					suggestionsString += fmt.Sprintf("\t%v\n", s)
 				}
 			}
 		}
-		return commandFound, a, fmt.Errorf("unknown command %q for %q%s", argsWOflags[0], commandFound.CommandPath(), suggestions)
+		return commandFound, a, fmt.Errorf("unknown command %q for %q%s", argsWOflags[0], commandFound.CommandPath(), suggestionsString)
 	}
 
 	return commandFound, a, nil
 }
 
+func (c *Command) SuggestionsFor(typedName string) []string {
+	suggestions := []string{}
+	for _, cmd := range c.commands {
+		if cmd.IsAvailableCommand() {
+			levenshteinDistance := ld(typedName, cmd.Name(), true)
+			suggestByLevenshtein := levenshteinDistance <= c.SuggestionsMinimumDistance
+			suggestByPrefix := strings.HasPrefix(strings.ToLower(cmd.Name()), strings.ToLower(typedName))
+			if suggestByLevenshtein || suggestByPrefix {
+				suggestions = append(suggestions, cmd.Name())
+			}
+			for _, explicitSuggestion := range cmd.SuggestFor {
+				if strings.EqualFold(typedName, explicitSuggestion) {
+					suggestions = append(suggestions, cmd.Name())
+				}
+			}
+		}
+	}
+	return suggestions
+}
+
 func (c *Command) Root() *Command {
 	var findRoot func(*Command) *Command
 


Test patch:
diff --git a/cobra_test.go b/cobra_test.go
index c9eef5d..f4814ea 100644
--- a/cobra_test.go
+++ b/cobra_test.go
@@ -82,9 +82,10 @@ var cmdDeprecated = &Command{
 }
 
 var cmdTimes = &Command{
-	Use:   "times [# times] [string to echo]",
-	Short: "Echo anything to the screen more times",
-	Long:  `a slightly useless command for testing.`,
+	Use:        "times [# times] [string to echo]",
+	SuggestFor: []string{"counts"},
+	Short:      "Echo anything to the screen more times",
+	Long:       `a slightly useless command for testing.`,
 	PersistentPreRun: func(cmd *Command, args []string) {
 		timesPersPre = args
 	},
@@ -816,22 +817,33 @@ func TestRootSuggestions(t *testing.T) {
 	cmd.AddCommand(cmdTimes)
 
 	tests := map[string]string{
-		"time":  "times",
-		"tiems": "times",
-		"timeS": "times",
-		"rimes": "times",
+		"time":     "times",
+		"tiems":    "times",
+		"tims":     "times",
+		"timeS":    "times",
+		"rimes":    "times",
+		"ti":       "times",
+		"t":        "times",
+		"timely":   "times",
+		"ri":       "",
+		"timezone": "",
+		"foo":      "",
+		"counts":   "times",
 	}
 
 	for typo, suggestion := range tests {
-		cmd.DisableSuggestions = false
-		result := simpleTester(cmd, typo)
-		if expected := fmt.Sprintf(outputWithSuggestions, typo, suggestion); result.Output != expected {
-			t.Errorf("Unexpected response.\nExpecting to be:\n %q\nGot:\n %q\n", expected, result.Output)
-		}
-		cmd.DisableSuggestions = true
-		result = simpleTester(cmd, typo)
-		if expected := fmt.Sprintf(outputWithoutSuggestions, typo); result.Output != expected {
-			t.Errorf("Unexpected response.\nExpecting to be:\n %q\nGot:\n %q\n", expected, result.Output)
+		for _, suggestionsDisabled := range []bool{false, true} {
+			cmd.DisableSuggestions = suggestionsDisabled
+			result := simpleTester(cmd, typo)
+			expected := ""
+			if len(suggestion) == 0 || suggestionsDisabled {
+				expected = fmt.Sprintf(outputWithoutSuggestions, typo)
+			} else {
+				expected = fmt.Sprintf(outputWithSuggestions, typo, suggestion)
+			}
+			if result.Output != expected {
+				t.Errorf("Unexpected response.\nExpecting to be:\n %q\nGot:\n %q\n", expected, result.Output)
+			}
 		}
 	}
 }