From b75af582e36cc033e6b6fef512b125177f611a2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Carlos=20Ch=C3=A1vez?= <jcchavezs@gmail.com>
Date: Thu, 15 Sep 2022 23:20:35 +0200
Subject: [PATCH] feat: adds alias for the kebab cases of the original targets.

Most of the experience in make is around chaining targets using kebab case e.g. make build test e2e-test which isn't supported by mage. This change automatically adds alias for the kebabcase version of the targets if they don't exist.
---
 mage/main.go                        | 34 ++++++++++++++++++++-
 mage/main_test.go                   | 46 +++++++++++++++++++++++++++++
 mage/testdata/kebabcase/magefile.go | 15 ++++++++++
 3 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 mage/testdata/kebabcase/magefile.go

diff --git a/mage/main.go b/mage/main.go
index a41e7435..4bcc707e 100644
--- a/mage/main.go
+++ b/mage/main.go
@@ -589,6 +589,38 @@ func Compile(goos, goarch, ldflags, magePath, goCmd, compileTo string, gofiles [
 	return nil
 }
 
+var (
+	matchFirstCap = regexp.MustCompile("(.)([A-Z][a-z]+)")
+	matchAllCap   = regexp.MustCompile("([a-z0-9])([A-Z])")
+)
+
+// camelToKebab turns a camelcase string into a kebab case one.
+func camelToKebab(s string) string {
+	ks := matchFirstCap.ReplaceAllString(s, "${1}-${2}")
+	ks = matchAllCap.ReplaceAllString(ks, "${1}-${2}")
+	return strings.ToLower(ks)
+}
+
+// backfillKebabAliases backfill the existing alias with those infered from camelcase targets.
+func backfillKebabAliases(aliases map[string]*parse.Function, funcs []*parse.Function) map[string]*parse.Function {
+	newAliases := aliases
+	if newAliases == nil {
+		newAliases = make(map[string]*parse.Function)
+	}
+	for _, f := range funcs {
+		kebabAlias := camelToKebab(f.Name)
+		if kebabAlias == f.Name {
+			continue
+		}
+
+		if _, ok := newAliases[f.Name]; !ok {
+			newAliases[kebabAlias] = f
+		}
+	}
+
+	return newAliases
+}
+
 // GenerateMainfile generates the mage mainfile at path.
 func GenerateMainfile(binaryName, path string, info *parse.PkgInfo) error {
 	debug.Println("Creating mainfile at", path)
@@ -601,7 +633,7 @@ func GenerateMainfile(binaryName, path string, info *parse.PkgInfo) error {
 	data := mainfileTemplateData{
 		Description: info.Description,
 		Funcs:       info.Funcs,
-		Aliases:     info.Aliases,
+		Aliases:     backfillKebabAliases(info.Aliases, info.Funcs),
 		Imports:     info.Imports,
 		BinaryName:  binaryName,
 	}
diff --git a/mage/main_test.go b/mage/main_test.go
index 2074c64a..06b04c19 100644
--- a/mage/main_test.go
+++ b/mage/main_test.go
@@ -1731,6 +1731,24 @@ func TestNamespaceDefault(t *testing.T) {
 func TestAliasToImport(t *testing.T) {
 }
 
+func TestAliasToKebabCase(t *testing.T) {
+	stdout := &bytes.Buffer{}
+	inv := Invocation{
+		Dir:    "./testdata/kebabcase",
+		Stderr: io.Discard,
+		Stdout: stdout,
+		Args:   []string{"fooBar", "foo-bar"},
+	}
+	code := Invoke(inv)
+	if code != 0 {
+		t.Fatalf("expected 0, but got %v", code)
+	}
+	expected := "FooBar\nFooBar\n"
+	if stdout.String() != expected {
+		t.Fatalf("expected %q, but got %q", expected, stdout.String())
+	}
+}
+
 func TestWrongDependency(t *testing.T) {
 	stderr := &bytes.Buffer{}
 	inv := Invocation{
@@ -1801,3 +1819,31 @@ func fileData(file string) (exeType, archSize, error) {
 	}
 	return -1, -1, fmt.Errorf("unrecognized executable format")
 }
+
+func TestCamelToKebab(t *testing.T) {
+	testCases := []struct {
+		camelCaseWord string
+		kebabWord     string
+	}{
+		{
+			camelCaseWord: "FizzBazz",
+			kebabWord:     "fizz-bazz",
+		},
+		{
+			camelCaseWord: "C",
+			kebabWord:     "c",
+		},
+		{
+			camelCaseWord: "DoSomeHTTPStuff",
+			kebabWord:     "do-some-http-stuff",
+		},
+	}
+
+	for _, tCase := range testCases {
+		t.Run(tCase.camelCaseWord, func(t *testing.T) {
+			if want, have := tCase.kebabWord, camelToKebab(tCase.camelCaseWord); want != have {
+				t.Errorf("unexpected transformation, want %q, have %q", want, have)
+			}
+		})
+	}
+}
diff --git a/mage/testdata/kebabcase/magefile.go b/mage/testdata/kebabcase/magefile.go
new file mode 100644
index 00000000..615ee944
--- /dev/null
+++ b/mage/testdata/kebabcase/magefile.go
@@ -0,0 +1,15 @@
+//go:build mage
+// +build mage
+
+package main
+
+import (
+	"fmt"
+)
+
+// No default so we can check the list().
+
+// Prints out 'FooBar'.
+func FooBar() {
+	fmt.Println("FooBar")
+}