add context.Context to cli.Context

app_test.go

@@ -236,7 +236,7 @@ func ExampleApp_Run_shellComplete() {
 	os.Args = []string{"greet", fmt.Sprintf("--%s", genCompName())}
 
 	app := &App{
-		Name: "greet",
+		Name:                  "greet",
 		EnableShellCompletion: true,
 		Commands: []*Command{
 			{
@@ -525,6 +525,8 @@ func TestApp_ParseSliceFlags(t *testing.T) {
 			},
 		},
 	}
+	var _ = parsedOption
+	var _ = firstArg
 
 	app.Run([]string{"", "cmd", "-p", "22", "-p", "80", "-ip", "8.8.8.8", "-ip", "8.8.4.4", "my-arg"})
 

context.go

@@ -1,18 +1,22 @@
 package cli
 
 import (
+	"context"
 	"errors"
 	"flag"
 	"os"
+	"os/signal"
 	"reflect"
 	"strings"
+	"syscall"
 )
 
 // Context is a type that is passed through to
 // each Handler action in a cli application. Context
 // can be used to retrieve context-specific args and
 // parsed command-line options.
 type Context struct {
+	context.Context
 	App           *App
 	Command       *Command
 	shellComplete bool
@@ -24,10 +28,20 @@ type Context struct {
 // NewContext creates a new context. For use in when invoking an App or Command action.
 func NewContext(app *App, set *flag.FlagSet, parentCtx *Context) *Context {
 	c := &Context{App: app, flagSet: set, parentContext: parentCtx}
-
 	if parentCtx != nil {
+		c.Context = parentCtx.Context
 		c.shellComplete = parentCtx.shellComplete
 	}
+	if c.Context == nil {
+		ctx, cancel := context.WithCancel(context.Background())
+		go func() {
+			defer cancel()
+			sigs := make(chan os.Signal, 1)
+			signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
+			<-sigs
+		}()
+		c.Context = ctx
+	}
 
 	return c
 }

context_test.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"context"
 	"flag"
 	"sort"
 	"testing"
@@ -262,3 +263,33 @@ func TestContext_lookupFlagSet(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestNonNilContext(t *testing.T) {
+	ctx := NewContext(nil, nil, nil)
+	if ctx.Context == nil {
+		t.Fatal("expected a non nil context when no parent is present")
+	}
+}
+
+// TestContextPropagation tests that
+// *cli.Context always has a valid
+// context.Context
+func TestContextPropagation(t *testing.T) {
+	parent := NewContext(nil, nil, nil)
+	parent.Context = context.WithValue(context.Background(), "key", "val")
+	ctx := NewContext(nil, nil, parent)
+	val := ctx.Value("key")
+	if val == nil {
+		t.Fatal("expected a parent context to be inherited but got nil")
+	}
+	valstr, _ := val.(string)
+	if valstr != "val" {
+		t.Fatalf("expected the context value to be %q but got %q", "val", valstr)
+	}
+	parent = NewContext(nil, nil, nil)
+	parent.Context = nil
+	ctx = NewContext(nil, nil, parent)
+	if ctx.Context == nil {
+		t.Fatal("expected context to not be nil even if the parent's context is nil")
+	}
+}