test(13-04): add failing tests for IconButton, UIIcon, Space, and Button icon wiring (RED)

backend/internal/web/ui/ui_test.go

@@ -397,3 +397,70 @@ func TestTable_RendersShell(t *testing.T) {
 		}
 	}
 }
+
+// Phase 13 Plan 04 — IconButton, UIIcon, Space, and Button icon wiring tests (TDD RED)
+
+func TestIconButton_GhostNeutral(t *testing.T) {
+	out := render(t, context.Background(), IconButton(IconButtonProps{
+		Icon:    "plus",
+		Variant: IconButtonVariantNeutral,
+		Tone:    IconButtonToneGhost,
+		Label:   "Add",
+	}))
+	if !strings.Contains(out, "borderless-icon-button") {
+		t.Errorf("expected borderless-icon-button class; got: %s", out)
+	}
+	if !strings.Contains(out, `aria-label="Add"`) {
+		t.Errorf("expected aria-label=\"Add\"; got: %s", out)
+	}
+}
+
+func TestIconButton_SolidDanger(t *testing.T) {
+	out := render(t, context.Background(), IconButton(IconButtonProps{
+		Icon:    "trash",
+		Variant: IconButtonVariantDanger,
+		Tone:    IconButtonToneSolid,
+		Label:   "Delete",
+	}))
+	if !strings.Contains(out, "ui-icon-button-solid") {
+		t.Errorf("expected ui-icon-button-solid class; got: %s", out)
+	}
+	if !strings.Contains(out, "ui-icon-button-danger") {
+		t.Errorf("expected ui-icon-button-danger class; got: %s", out)
+	}
+}
+
+func TestUIIcon_Plus(t *testing.T) {
+	out := render(t, context.Background(), UIIcon("plus"))
+	if !strings.Contains(out, "<svg") {
+		t.Errorf("expected <svg in output for 'plus' icon; got: %s", out)
+	}
+}
+
+func TestUIIcon_Fallback(t *testing.T) {
+	out := render(t, context.Background(), UIIcon("unknown-kind"))
+	if !strings.Contains(out, "<span") {
+		t.Errorf("expected <span fallback for unknown icon kind; got: %s", out)
+	}
+}
+
+func TestSpaceX_MD(t *testing.T) {
+	out := render(t, context.Background(), SpaceX(SpaceProps{Size: SpacingStepMD}))
+	if !strings.Contains(out, "ui-space-x-md") {
+		t.Errorf("expected ui-space-x-md in output; got: %s", out)
+	}
+}
+
+func TestSpaceY_LG(t *testing.T) {
+	out := render(t, context.Background(), SpaceY(SpaceProps{Size: SpacingStepLG}))
+	if !strings.Contains(out, "ui-space-y-lg") {
+		t.Errorf("expected ui-space-y-lg in output; got: %s", out)
+	}
+}
+
+func TestButton_IconRendered(t *testing.T) {
+	out := render(t, context.Background(), Button(ButtonProps{Label: "Add", Icon: "plus"}))
+	if !strings.Contains(out, "<svg") {
+		t.Errorf("expected <svg in output when Button.Icon is set; got: %s", out)
+	}
+}