add mcp tests

Author: natefinch

mage/main.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/magefile/mage/internal"
+	magemcp "github.com/magefile/mage/mcp"
 	"github.com/magefile/mage/mg"
 	"github.com/magefile/mage/parse"
 	"github.com/magefile/mage/sh"
@@ -106,6 +107,7 @@ type Invocation struct {
 	GOOS       string        // sets the GOOS when producing a binary with -compileout
 	GOARCH     string        // sets the GOARCH when producing a binary with -compileout
 	Ldflags    string        // sets the ldflags when producing a binary with -compileout
+	MCP        bool          // generate an MCP server instead of a CLI
 	Stdout     io.Writer     // writer to write stdout messages to
 	Stderr     io.Writer     // writer to write stderr messages to
 	Stdin      io.Reader     // reader to read stdin from
@@ -219,6 +221,7 @@ func Parse(stderr, stdout io.Writer, args []string) (inv Invocation, cmd Command
 	fs.StringVar(&inv.GOOS, "goos", "", "set GOOS for binary produced with -compile")
 	fs.StringVar(&inv.GOARCH, "goarch", "", "set GOARCH for binary produced with -compile")
 	fs.StringVar(&inv.Ldflags, "ldflags", "", "set ldflags for binary produced with -compile")
+	fs.BoolVar(&inv.MCP, "mcp", false, "generate an MCP server instead of a CLI")
 
 	// commands below
 
@@ -257,6 +260,7 @@ Options:
 		      use the given go binary to compile the output (default: "go")
   -goos       sets the GOOS for the binary created by -compile (default: current OS)
   -ldflags    sets the ldflags for the binary created by -compile (default: "")
+  -mcp        generate an MCP server instead of a CLI
   -multiline  retain line returns in help docs (default: convert to spaces)
   -h          show description of a target
   -keep       keep intermediate mage files around after running
@@ -320,6 +324,10 @@ Options:
 		return inv, cmd, errors.New("-goos and -goarch only apply when running with -compile")
 	}
 
+	if inv.MCP && cmd != None && cmd != CompileStatic {
+		return inv, cmd, errors.New("-mcp cannot be combined with -init, -clean, or -version")
+	}
+
 	inv.Args = fs.Args()
 	if inv.Help && len(inv.Args) > 1 {
 		return inv, cmd, errors.New("-h can only show help for a single target")
@@ -450,7 +458,11 @@ func Invoke(inv Invocation) int {
 		binaryName = filepath.Base(inv.CompileOut)
 	}
 
-	err = GenerateMainfile(binaryName, main, info)
+	if inv.MCP {
+		err = magemcp.GenerateMainfile(binaryName, main, info)
+	} else {
+		err = GenerateMainfile(binaryName, main, info)
+	}
 	if err != nil {
 		errlog.Println("Error:", err)
 		return 1

mage/main_test.go

@@ -1917,3 +1917,61 @@ func fileData(file string) (exeType, archSize, error) {
 	}
 	return -1, -1, errors.New("unrecognized executable format")
 }
+
+func TestParseMCPFlag(t *testing.T) {
+	buf := &bytes.Buffer{}
+	inv, _, err := Parse(io.Discard, buf, []string{"-mcp"})
+	if err != nil {
+		t.Fatal("unexpected error", err)
+	}
+	if !inv.MCP {
+		t.Error("expected MCP to be true")
+	}
+}
+
+func TestParseMCPWithCompile(t *testing.T) {
+	buf := &bytes.Buffer{}
+	inv, cmd, err := Parse(io.Discard, buf, []string{"-mcp", "-compile", "output"})
+	if err != nil {
+		t.Fatal("unexpected error", err)
+	}
+	if !inv.MCP {
+		t.Error("expected MCP to be true")
+	}
+	if cmd != CompileStatic {
+		t.Errorf("expected CompileStatic command, got %v", cmd)
+	}
+}
+
+func TestParseMCPWithInit(t *testing.T) {
+	buf := &bytes.Buffer{}
+	_, _, err := Parse(io.Discard, buf, []string{"-mcp", "-init"})
+	if err == nil {
+		t.Fatal("expected error combining -mcp with -init")
+	}
+	if !strings.Contains(err.Error(), "-mcp cannot be combined") {
+		t.Fatalf("unexpected error message: %v", err)
+	}
+}
+
+func TestParseMCPWithClean(t *testing.T) {
+	buf := &bytes.Buffer{}
+	_, _, err := Parse(io.Discard, buf, []string{"-mcp", "-clean"})
+	if err == nil {
+		t.Fatal("expected error combining -mcp with -clean")
+	}
+	if !strings.Contains(err.Error(), "-mcp cannot be combined") {
+		t.Fatalf("unexpected error message: %v", err)
+	}
+}
+
+func TestParseMCPWithVersion(t *testing.T) {
+	buf := &bytes.Buffer{}
+	_, _, err := Parse(io.Discard, buf, []string{"-mcp", "-version"})
+	if err == nil {
+		t.Fatal("expected error combining -mcp with -version")
+	}
+	if !strings.Contains(err.Error(), "-mcp cannot be combined") {
+		t.Fatalf("unexpected error message: %v", err)
+	}
+}