go/cli: an outcome not known is not a refusal; the Go binding is checked in the Go toolchain

Review of hq ADR 0272: a line whose answer did not come in time may have
run, and saying "nothing ran" there is a lie. Answer.Unknown and NotKnown
say it may have run and name the call to look at.

The SDK's repo-check ran in the TypeScript toolchain only and said
"NOT TESTED HERE: go/". go/merge-check.sh now runs the Go binding in the Go
toolchain, declared by the root check (mesh-check-also), as the lab does.

Released as go/v0.1.9 (go/v0.1.8 is mesh-sdk #12's).

go/cli/cli.go

@@ -54,11 +54,24 @@ type Answer struct {
 	Refused string `json:"refused,omitempty"`
 	// Cut says the output was longer than one bus message and was cut there.
 	Cut bool `json:"cut,omitempty"`
+	// Unknown says the line was asked and its outcome is not known: no answer came in time, and it may have
+	// run. Never said as a refusal, which means nothing ran.
+	Unknown string `json:"unknown,omitempty"`
 }
 
 // Refusal is an answer saying that nothing ran, and why.
 func Refusal(why string) Answer { return Answer{Exit: 1, Refused: why} }
 
+// NotKnown is an answer saying the line was asked and what came of it is not known: it may have run. call is
+// the controller's call the line runs as, when it is known, which `calls` answers.
+func NotKnown(call, why string) Answer {
+	where := "the controller's `calls` lists what came of each line"
+	if call != "" {
+		where = "see the call " + call + " (`calls " + call + "`)"
+	}
+	return Answer{Exit: 1, Unknown: why + "; the line may have run — " + where}
+}
+
 // ErrTooLong is a request or an answer over its bound.
 var ErrTooLong = errors.New("longer than the protocol allows")
 

go/cli/cli_test.go

@@ -26,7 +26,8 @@ func TestARequestAndAnAnswerSurviveTheirRoundTrip(t *testing.T) {
 	}
 
 	b.Reset()
-	sent := Answer{Stdout: []byte("ok\n\xff"), Stderr: []byte("said"), Exit: 3, Terminal: true, Why: "the terminal", Cut: true}
+	sent := Answer{Stdout: []byte("ok\n\xff"), Stderr: []byte("said"), Exit: 3, Terminal: true, Why: "the terminal", Cut: true,
+		Unknown: "no answer; the line may have run — see the call call-1"}
 	if err := WriteAnswer(&b, sent); err != nil {
 		t.Fatal(err)
 	}
@@ -34,7 +35,8 @@ func TestARequestAndAnAnswerSurviveTheirRoundTrip(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !bytes.Equal(a.Stdout, sent.Stdout) || string(a.Stderr) != "said" || a.Exit != 3 || !a.Terminal || a.Why != sent.Why || !a.Cut {
+	if !bytes.Equal(a.Stdout, sent.Stdout) || string(a.Stderr) != "said" || a.Exit != 3 || !a.Terminal || a.Why != sent.Why || !a.Cut ||
+		a.Unknown != sent.Unknown {
 		t.Fatalf("the answer came back as %+v", a)
 	}
 }
@@ -90,3 +92,14 @@ func TestAskSpeaksTheProtocolOverASocket(t *testing.T) {
 		t.Fatalf("a missing socket was not said: %v", err)
 	}
 }
+
+// An outcome not known is never a refusal: it says the line may have run, and exits non-zero.
+func TestAnUnknownOutcomeIsNotARefusal(t *testing.T) {
+	a := NotKnown("call-7", "no answer within 6m0s")
+	if a.Refused != "" || a.Exit == 0 || !strings.Contains(a.Unknown, "may have run") || !strings.Contains(a.Unknown, "call-7") {
+		t.Fatalf("an unknown outcome reads as %+v", a)
+	}
+	if b := NotKnown("", "no answer"); strings.Contains(b.Unknown, "call ") {
+		t.Fatalf("an unknown outcome with no call names one: %+v", b)
+	}
+}