fix: emit structured reference errors and add JSON output tests (#134)

Route check --references validation errors through the linter formatter so
--format json produces machine-readable output instead of plain text.

Add tests for showAccessOnMicroflow/showAccessOnPage JSON output and empty-
result JSON output for showConstants and showPublishedRestServices.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ako

cmd/mxcli/cmd_check.go

@@ -160,11 +160,23 @@ Examples:
 			// Validate the program (considers objects defined within the script)
 			validationErrors := exec.ValidateProgram(prog)
 			if len(validationErrors) > 0 {
-				fmt.Fprintf(os.Stderr, "Reference errors:\n")
-				for _, err := range validationErrors {
-					fmt.Fprintf(os.Stderr, "  %v\n", err)
+				if isStructured {
+					var refViolations []linter.Violation
+					for _, err := range validationErrors {
+						refViolations = append(refViolations, linter.Violation{
+							RuleID:   "MDL-REF",
+							Severity: linter.SeverityError,
+							Message:  err.Error(),
+						})
+					}
+					formatter.Format(refViolations, os.Stderr)
+				} else {
+					fmt.Fprintf(os.Stderr, "Reference errors:\n")
+					for _, err := range validationErrors {
+						fmt.Fprintf(os.Stderr, "  %v\n", err)
+					}
+					fmt.Fprintf(os.Stderr, "\n✗ %d reference error(s) found\n", len(validationErrors))
 				}
-				fmt.Fprintf(os.Stderr, "\n✗ %d reference error(s) found\n", len(validationErrors))
 				os.Exit(1)
 			}
 			if !isStructured {

mdl/executor/cmd_json_mock_test.go

@@ -5,6 +5,7 @@ package executor
 import (
 	"testing"
 
+	"github.com/mendixlabs/mxcli/mdl/ast"
 	"github.com/mendixlabs/mxcli/mdl/backend/mock"
 	"github.com/mendixlabs/mxcli/mdl/types"
 	"github.com/mendixlabs/mxcli/model"
@@ -526,3 +527,75 @@ func TestListDataTransformers_Mock_JSON(t *testing.T) {
 	assertValidJSON(t, buf.String())
 	assertContainsStr(t, buf.String(), "Transform1")
 }
+
+func TestShowAccessOnMicroflow_Mock_JSON(t *testing.T) {
+	mod := mkModule("MyModule")
+	h := mkHierarchy(mod)
+	mf := mkMicroflow(mod.ID, "ACT_DoStuff")
+	mf.AllowedModuleRoles = []model.ID{"MyModule.User", "MyModule.Admin"}
+	withContainer(h, mf.ContainerID, mod.ID)
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc:    func() bool { return true },
+		ListMicroflowsFunc: func() ([]*microflows.Microflow, error) { return []*microflows.Microflow{mf}, nil },
+	}
+
+	name := &ast.QualifiedName{Module: "MyModule", Name: "ACT_DoStuff"}
+	ctx, buf := newMockCtx(t, withBackend(mb), withFormat(FormatJSON), withHierarchy(h))
+	assertNoError(t, showAccessOnMicroflow(ctx, name))
+	assertValidJSON(t, buf.String())
+	assertContainsStr(t, buf.String(), "User")
+}
+
+func TestShowAccessOnPage_Mock_JSON(t *testing.T) {
+	mod := mkModule("MyModule")
+	h := mkHierarchy(mod)
+	pg := mkPage(mod.ID, "Page_Home")
+	pg.AllowedRoles = []model.ID{"MyModule.User"}
+	withContainer(h, pg.ContainerID, mod.ID)
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc: func() bool { return true },
+		ListPagesFunc:   func() ([]*pages.Page, error) { return []*pages.Page{pg}, nil },
+	}
+
+	name := &ast.QualifiedName{Module: "MyModule", Name: "Page_Home"}
+	ctx, buf := newMockCtx(t, withBackend(mb), withFormat(FormatJSON), withHierarchy(h))
+	assertNoError(t, showAccessOnPage(ctx, name))
+	assertValidJSON(t, buf.String())
+	assertContainsStr(t, buf.String(), "User")
+}
+
+// TestShowConstants_Mock_JSON_EmptyResult verifies that an empty result still
+// produces valid JSON (not the "No ... found." plain-text message).
+func TestShowConstants_Mock_JSON_EmptyResult(t *testing.T) {
+	mod := mkModule("MyModule")
+	h := mkHierarchy(mod)
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc:   func() bool { return true },
+		ListConstantsFunc: func() ([]*model.Constant, error) { return nil, nil },
+	}
+
+	ctx, buf := newMockCtx(t, withBackend(mb), withFormat(FormatJSON), withHierarchy(h))
+	assertNoError(t, showConstants(ctx, ""))
+	assertValidJSON(t, buf.String())
+	assertNotContainsStr(t, buf.String(), "No constants found")
+}
+
+// TestShowPublishedRestServices_Mock_JSON_EmptyResult verifies that an empty
+// result still produces valid JSON in JSON mode.
+func TestShowPublishedRestServices_Mock_JSON_EmptyResult(t *testing.T) {
+	mod := mkModule("MyModule")
+	h := mkHierarchy(mod)
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc:               func() bool { return true },
+		ListPublishedRestServicesFunc: func() ([]*model.PublishedRestService, error) { return nil, nil },
+	}
+
+	ctx, buf := newMockCtx(t, withBackend(mb), withFormat(FormatJSON), withHierarchy(h))
+	assertNoError(t, showPublishedRestServices(ctx, ""))
+	assertValidJSON(t, buf.String())
+	assertNotContainsStr(t, buf.String(), "No published REST services found")
+}