Validate configuration source keys and overrides

internal/config/config_test.go

@@ -1066,6 +1066,44 @@ func TestInvalidConfigProducesActionableError(t *testing.T) {
 	}
 }
 
+func TestMissingSourcePoliciesOnlyAllowSupportedOptionalSources(t *testing.T) {
+	for _, source := range []string{
+		MissingSourceObservations,
+		MissingSourceCurrent,
+		MissingSourceNarrative,
+		MissingSourceAlerts,
+		MissingSourceDiscussion,
+		MissingSourceWeatherStory,
+		MissingSourceSPCConvectiveOutlooks,
+	} {
+		t.Run("supported_"+source, func(t *testing.T) {
+			cfg := Defaults()
+			cfg.MissingSource.Sources = map[string]MissingSourcePolicy{source: MissingSourceNone}
+			if err := Validate(cfg); err != nil {
+				t.Fatalf("Validate() error = %v", err)
+			}
+			loaded, err := LoadFile(writeConfig(t, "missing_source:\n  sources:\n    "+source+": none\n"))
+			if err != nil {
+				t.Fatalf("LoadFile() error = %v", err)
+			}
+			if loaded.MissingSource.Sources[source] != MissingSourceNone {
+				t.Fatalf("loaded source policy = %q, want none", loaded.MissingSource.Sources[source])
+			}
+		})
+	}
+
+	for _, source := range []string{"alert", "unknown", "hourly", ""} {
+		t.Run("unsupported_"+source, func(t *testing.T) {
+			cfg := Defaults()
+			cfg.MissingSource.Sources = map[string]MissingSourcePolicy{source: MissingSourceWarn}
+			err := Validate(cfg)
+			if err == nil || !strings.Contains(err.Error(), "missing_source.sources") {
+				t.Fatalf("Validate() error = %v, want unsupported source error", err)
+			}
+		})
+	}
+}
+
 func TestLoadAppliesOverrides(t *testing.T) {
 	cfg, err := Load(LoadOptions{Units: "metric", Timezone: "+09:30"})
 	if err != nil {