Expand Gotlin language and tooling

internal/lang/enum_test.go

@@ -0,0 +1,79 @@
+package lang
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestGenerateRustStyleEnumAndExhaustiveMatch(t *testing.T) {
+	prog, err := Parse(`
+package demo
+enum PaymentResult { Accepted(String), Rejected(String), Pending }
+fun describe(result: PaymentResult): String {
+    var description = ""
+    match (result) {
+        PaymentResult::Accepted(id) -> { description = id }
+        PaymentResult::Rejected(reason) -> { description = reason }
+        PaymentResult::Pending -> { description = "pending" }
+    }
+    return description
+}
+fun main() { println(describe(PaymentResult::Accepted("p1"))) }
+`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := GenerateGo(prog)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{"type PaymentResult interface", "type PaymentResultAccepted struct", "&PaymentResultAccepted{Value0: \"p1\"}", "case *PaymentResultRejected:", "reason := gotlinMatch1.Value0"} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q:\n%s", want, out)
+		}
+	}
+}
+
+func TestRejectNonExhaustiveEnumMatch(t *testing.T) {
+	prog, err := Parse(`package demo
+enum Result { Ok, Error(String) }
+fun use(result: Result) { match (result) { Result::Ok -> { println("ok") } } }`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = GenerateGo(prog)
+	if err == nil || !strings.Contains(err.Error(), "missing Error") {
+		t.Fatalf("expected exhaustive-match error, got %v", err)
+	}
+}
+
+func TestRejectWrongVariantPayloadCount(t *testing.T) {
+	prog, err := Parse(`package demo
+enum Result { Ok(String) }
+fun main() { val result = Result::Ok() }`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = GenerateGo(prog)
+	if err == nil || !strings.Contains(err.Error(), "expects 1 values") {
+		t.Fatalf("expected payload error, got %v", err)
+	}
+}
+
+func TestPayloadlessEnumUsesExactVariantStrings(t *testing.T) {
+	prog, err := Parse(`package demo
+enum Status { PendingReservation, Initiated }
+fun main() { println(Status::PendingReservation) }`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := GenerateGo(prog)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{`type Status string`, `StatusPendingReservation`, `"PendingReservation"`, `StatusInitiated`, `"Initiated"`} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q:\n%s", want, out)
+		}
+	}
+}