Install command aliases atomically

registry_test.go

@@ -2,7 +2,10 @@ package commandkit
 
 import (
 	"errors"
+	"fmt"
 	"testing"
+
+	"gitea.maximumdirect.net/eric/CommandKit/internal/commandpath"
 )
 
 type registryInput struct{ value string }
@@ -41,11 +44,11 @@ func TestCapturedDeclarationsRetainCallbacksWithoutCallingThem(t *testing.T) {
 }
 
 func TestRoutingRuleFactoriesCaptureNormalizedValues(t *testing.T) {
-	commandRule := Alias("  old\tpath ", "new path")
+	commandRule := Alias("  old\tpath ", " new ")
 	if got, want := commandRule.record.sourcePath.String(), "old path"; got != want {
 		t.Fatalf("source path = %q, want %q", got, want)
 	}
-	if got, want := commandRule.record.targetPath.String(), "new path"; got != want {
+	if got, want := commandRule.record.targetPath.String(), "new"; got != want {
 		t.Fatalf("target path = %q, want %q", got, want)
 	}
 	globalRule := FlagAlias("--colour", "-c")
@@ -117,6 +120,155 @@ func TestNilAndZeroDeclarationsFailWithoutMutation(t *testing.T) {
 	}
 }
 
+func TestAliasTargetsCanBeDeclaredInEitherOrder(t *testing.T) {
+	canonical := simpleRunnable("canonical")
+	for name, declarations := range map[string][]Declaration{
+		"targets last": {
+			Alias("shortcut", "alternate"),
+			Alias("alternate", "canonical"),
+			canonical,
+		},
+		"targets first": {
+			canonical,
+			Alias("alternate", "canonical"),
+			Alias("shortcut", "alternate"),
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			app, err := New(Identity{Name: "Example"}, declarations...)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got := app.aliases.Resolve(commandpath.Path{"shortcut"}); !got.Equal(commandpath.Path{"canonical"}) {
+				t.Fatalf("shortcut resolves to %#v", got)
+			}
+		})
+	}
+}
+
+func TestIdenticalCommandAliasesAreIdempotentAcrossRegistrations(t *testing.T) {
+	app, err := New(Identity{Name: "Example"}, simpleRunnable("canonical"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	rule := Alias("shortcut", "canonical")
+	if err := app.Register(rule, Alias(" shortcut ", " canonical ")); err != nil {
+		t.Fatal(err)
+	}
+	if len(app.routingRules) != 1 {
+		t.Fatalf("routing rules = %d, want one normalized rule", len(app.routingRules))
+	}
+	snapshot := app.routeSnapshot()
+	if err := app.Register(Alias("shortcut", "canonical")); err != nil {
+		t.Fatal(err)
+	}
+	if len(app.routingRules) != 1 || app.routeSnapshot() != snapshot {
+		t.Fatal("identical registration changed aliases or invalidated the snapshot")
+	}
+}
+
+func TestCommandAliasesRejectMissingAndCompetingTargets(t *testing.T) {
+	if _, err := New(Identity{Name: "Example"}, Alias("shortcut", "missing")); err == nil {
+		t.Fatal("New() accepted a missing alias target")
+	}
+	_, err := New(Identity{Name: "Example"},
+		simpleRunnable("canonical"),
+		Alias("first", "canonical"),
+		Alias("second", "canonical"),
+		Alias("shortcut", "first"),
+		Alias("shortcut", "second"),
+	)
+	if err == nil {
+		t.Fatal("New() accepted competing declared targets with a shared endpoint")
+	}
+}
+
+func TestCommandAliasesRejectCanonicalRoutesAndOperands(t *testing.T) {
+	group := Group("group", "group", simpleRunnable("show"))
+	if _, err := New(Identity{Name: "Example"}, group, simpleRunnable("target"), Alias("group show", "target")); err == nil {
+		t.Fatal("New() accepted an alias source that replaces a canonical child")
+	}
+
+	run := runnableWithOperands("run", 1, 1)
+	if _, err := New(Identity{Name: "Example"}, run, simpleRunnable("inspect"), Alias("run full", "inspect")); err == nil {
+		t.Fatal("New() accepted an alias source that intercepts a valid operand")
+	}
+	if _, err := New(Identity{Name: "Example"}, run, Alias("fast", "run production")); err == nil {
+		t.Fatal("New() accepted an operand-bearing alias target")
+	}
+
+	promptkit := Group("promptkit", "promptkit", runnableWithOperands("test", 1, 1))
+	if _, err := New(Identity{Name: "Example"}, promptkit, Alias("promptkit test full", "promptkit test all")); err == nil {
+		t.Fatal("New() accepted an alias that replaces the test command's KIND operand")
+	}
+}
+
+func TestLongerAliasBeneathAlternateSpellingCanUseOperandWords(t *testing.T) {
+	app, err := New(Identity{Name: "Example"},
+		runnableWithOperands("run", 1, 1),
+		simpleRunnable("inspect"),
+		Alias("r", "run"),
+		Alias("r full", "inspect"),
+		Alias("run too many words", "inspect"),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := app.aliases.Resolve(commandpath.Path{"r", "full"}); !got.Equal(commandpath.Path{"inspect"}) {
+		t.Fatalf("longer alternate route resolves to %#v", got)
+	}
+}
+
+func TestFailedAliasRegistrationPreservesCommandsRulesAndSnapshot(t *testing.T) {
+	app, err := New(Identity{Name: "Example"}, simpleRunnable("canonical"), Alias("existing", "canonical"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	snapshot := app.routeSnapshot()
+	oldResolver := app.aliases
+	retained := errors.New("retained construction failure")
+	invalid := WithError(simpleRunnable("new"), fmt.Errorf("integration: %w", retained))
+	err = app.Register(invalid, Alias("later", "missing"))
+	if !errors.Is(err, retained) {
+		t.Fatalf("Register() error = %v, want retained cause", err)
+	}
+	if app.commands["new"] != nil || len(app.routingRules) != 1 || app.routeSnapshot() != snapshot || app.aliases != oldResolver {
+		t.Fatal("failed registration changed the app registry or derived metadata")
+	}
+}
+
+func TestNewCanonicalCommandIsCheckedAgainstExistingAliases(t *testing.T) {
+	app, err := New(Identity{Name: "Example"}, simpleRunnable("canonical"), Alias("shortcut", "canonical"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	snapshot := app.routeSnapshot()
+	if err := app.Register(simpleRunnable("shortcut")); err == nil {
+		t.Fatal("Register() accepted a canonical command that collides with an alias source")
+	}
+	if app.commands["shortcut"] != nil || len(app.routingRules) != 1 || app.routeSnapshot() != snapshot {
+		t.Fatal("failed canonical registration changed the app registry or snapshot")
+	}
+}
+
+func simpleRunnable(name string) Command {
+	return NewCommand(CommandSpec[struct{}]{
+		Name: name, Summary: name,
+		Run: func(Invocation, struct{}) Outcome { return Success() },
+	})
+}
+
+func runnableWithOperands(name string, min, max int) Command {
+	return NewCommand(CommandSpec[struct{}]{
+		Name: name, Summary: name,
+		Arguments: []Argument[struct{}]{RepeatArgument(ArgumentMeta{Name: "ARG"}, min, max,
+			func(value string) (string, error) { return value, nil },
+			func(*struct{}, Supplied[[]string]) {},
+		)},
+		Run: func(Invocation, struct{}) Outcome { return Success() },
+	})
+}
+
 func TestAppsHaveIndependentRegistries(t *testing.T) {
 	first, err := New(Identity{Name: "First"})
 	if err != nil {