Make the CLI nicer on an unknown command

cli/commands/unknown_command_test.go

@@ -0,0 +1,169 @@
+package commands
+
+import (
+	"strings"
+	"testing"
+
+	"miren.dev/mflags"
+	"miren.dev/runtime/pkg/labs"
+)
+
+// dispatchErr builds the full dispatcher and returns the error Execute produces,
+// so that tests can assert on what the user sees when a command is mistyped.
+func dispatchErr(t *testing.T, args ...string) error {
+	t.Helper()
+
+	d := mflags.NewDispatcher("miren")
+	RegisterAll(d)
+
+	return d.Execute(args)
+}
+
+// TestUnknownCommandSuggests guards MIR-1823: a mistyped command must name the
+// word that went wrong and point at the real one, rather than reporting a flag
+// parsing failure.
+func TestUnknownCommandSuggests(t *testing.T) {
+	labs.EnableAll()
+
+	cases := []struct {
+		args    []string
+		want    []string
+		notWant []string
+	}{
+		{
+			args:    []string{"depoy"},
+			want:    []string{`unknown command "depoy"`, "Did you mean?", "deploy", "miren --help"},
+			notWant: []string{"error parsing flags", "["},
+		},
+		{
+			// The old message reported "error parsing flags: unexpected
+			// arguments: [lst]" here.
+			args:    []string{"app", "lst"},
+			want:    []string{`unknown command "lst" for "miren app"`, "Did you mean?", "list", "miren app --help"},
+			notWant: []string{"error parsing flags", "["},
+		},
+		{
+			// Sections tolerate unknown flags, so this used to print help and
+			// exit 0 with no sign that anything was wrong.
+			args:    []string{"runner", "upgrde"},
+			want:    []string{`unknown command "upgrde" for "miren runner"`, "upgrade"},
+			notWant: []string{"error parsing flags"},
+		},
+		{
+			// Nothing is close to this, so no guess should be offered.
+			args:    []string{"zzzznotacommand"},
+			want:    []string{`unknown command "zzzznotacommand"`},
+			notWant: []string{"Did you mean?", "error parsing flags"},
+		},
+		{
+			// "version" has no sub-commands, so there is nothing to suggest —
+			// but the Go slice syntax and the flag-parsing prefix are still gone.
+			args:    []string{"version", "foo"},
+			want:    []string{`unexpected argument "foo"`},
+			notWant: []string{"error parsing flags", "[foo]"},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(strings.Join(c.args, "_"), func(t *testing.T) {
+			err := dispatchErr(t, c.args...)
+			if err == nil {
+				t.Fatalf("Execute(%v) returned no error", c.args)
+			}
+
+			got := err.Error()
+			for _, want := range c.want {
+				if !strings.Contains(got, want) {
+					t.Errorf("expected %q in error, got:\n%s", want, got)
+				}
+			}
+			for _, notWant := range c.notWant {
+				if strings.Contains(got, notWant) {
+					t.Errorf("did not expect %q in error, got:\n%s", notWant, got)
+				}
+			}
+		})
+	}
+}
+
+// TestUnknownFlagSuggests covers the same treatment for a mistyped flag name.
+func TestUnknownFlagSuggests(t *testing.T) {
+	labs.EnableAll()
+
+	cases := []struct {
+		args    []string
+		want    []string
+		notWant []string
+	}{
+		{
+			args:    []string{"deploy", "--aap", "x"},
+			want:    []string{"unknown flag: --aap", "Did you mean?", "--app"},
+			notWant: []string{"error parsing flags"},
+		},
+		{
+			args:    []string{"app", "list", "--forma", "json"},
+			want:    []string{"unknown flag: --forma", "--format"},
+			notWant: []string{"error parsing flags"},
+		},
+		{
+			// A single letter is too little to guess from.
+			args:    []string{"app", "list", "-Q"},
+			want:    []string{"unknown flag: -Q"},
+			notWant: []string{"Did you mean?"},
+		},
+		{
+			// No command word was typed at all, so there is nothing to call an
+			// unknown command — name the flag instead.
+			args:    []string{"--bogus"},
+			want:    []string{"unknown flag: --bogus"},
+			notWant: []string{`unknown command ""`},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(strings.Join(c.args, "_"), func(t *testing.T) {
+			err := dispatchErr(t, c.args...)
+			if err == nil {
+				t.Fatalf("Execute(%v) returned no error", c.args)
+			}
+
+			got := err.Error()
+			for _, want := range c.want {
+				if !strings.Contains(got, want) {
+					t.Errorf("expected %q in error, got:\n%s", want, got)
+				}
+			}
+			for _, notWant := range c.notWant {
+				if strings.Contains(got, notWant) {
+					t.Errorf("did not expect %q in error, got:\n%s", notWant, got)
+				}
+			}
+		})
+	}
+}
+
+// TestKnownCommandsAreNotMistakenForTypos pins the inputs the new check must
+// leave alone: help keywords, pass-through arguments, and global flags that
+// take a value.
+func TestKnownCommandsAreNotMistakenForTypos(t *testing.T) {
+	labs.EnableAll()
+
+	cases := [][]string{
+		{"app", "--help"},
+		{"app", "help"},
+		{"runner", "help"},
+		{"help", "runner"},
+		{"-C", "prod", "auth", "help"},
+		{"app", "run", "echo", "hello"},
+	}
+
+	for _, args := range cases {
+		t.Run(strings.Join(args, "_"), func(t *testing.T) {
+			if err := dispatchErr(t, args...); err != nil {
+				if strings.Contains(err.Error(), "unknown command") {
+					t.Errorf("Execute(%v) wrongly reported a typo: %v", args, err)
+				}
+			}
+		})
+	}
+}

go.mod

@@ -107,7 +107,7 @@ require (
 	gopkg.in/yaml.v3 v3.0.1
 	k8s.io/klog/v2 v2.130.1
 	miren.dev/lbd v0.0.0-20260224020427-8914d8db2233
-	miren.dev/mflags v0.0.0-20260910225849-7704913d5c9c
+	miren.dev/mflags v0.0.0-20260913023833-b11db8e63177
 	modernc.org/sqlite v1.45.0
 	sigs.k8s.io/knftables v0.0.21
 )

go.sum

@@ -1955,8 +1955,8 @@ k8s.io/klog/v2 v2.130.1 h1:n9Xl7H1Xvksem4KFG4PYbdQCQxqc/tTUyrgXaOhHSzk=
 k8s.io/klog/v2 v2.130.1/go.mod h1:3Jpz1GvMt720eyJH1ckRHK1EDfpxISzJ7I9OYgaDtPE=
 miren.dev/lbd v0.0.0-20260224020427-8914d8db2233 h1:9DxH7Dhnmu7hn1OA2JC5fHpLuVgAqBySws9GLNssLl4=
 miren.dev/lbd v0.0.0-20260224020427-8914d8db2233/go.mod h1:+x9fy2p45csBnGUJdqxCUmzlUTCipoVDbv6zIapTgDA=
-miren.dev/mflags v0.0.0-20260910225849-7704913d5c9c h1:x4XxiRPIEh64GV1DzDaxGoiMqj+9qYCOnFBW2h+L3Vs=
-miren.dev/mflags v0.0.0-20260910225849-7704913d5c9c/go.mod h1:G1eQ/upWVdO6BGT6dlh5Yqjt+9ncH5RUAKX6UKi1F9Q=
+miren.dev/mflags v0.0.0-20260913023833-b11db8e63177 h1:7w7JpoGLuFwv3WQHDeYQHyruWA6y+SLNuZIO4LOZggk=
+miren.dev/mflags v0.0.0-20260913023833-b11db8e63177/go.mod h1:G1eQ/upWVdO6BGT6dlh5Yqjt+9ncH5RUAKX6UKi1F9Q=
 modernc.org/cc/v4 v4.27.1 h1:9W30zRlYrefrDV2JE2O8VDtJ1yPGownxciz5rrbQZis=
 modernc.org/cc/v4 v4.27.1/go.mod h1:uVtb5OGqUKpoLWhqwNQo/8LwvoiEBLvZXIQ/SmO6mL0=
 modernc.org/ccgo/v4 v4.30.1 h1:4r4U1J6Fhj98NKfSjnPUN7Ze2c6MnAdL0hWw6+LrJpc=