test(core): add integration tests for public API surface

crates/draw-core/tests/integration.rs

@@ -0,0 +1,196 @@
+//! Integration tests exercising draw_core as an external consumer would —
+//! only `pub use` re-exports from the crate root, cross-module flows,
+//! and gaps in inline unit-test coverage (Binding round-trip, full pipeline).
+
+use draw_core::{
+    Binding, Document, Element, FreeDrawElement, LineElement, Point, ShapeElement, TextElement,
+    export_png, export_svg,
+};
+
+/// Build a document containing one of every Element variant.
+fn populated_doc(name: &str) -> Document {
+    let mut doc = Document::new(name.to_string());
+    doc.add_element(Element::Rectangle(ShapeElement::new(
+        "rect-1".into(),
+        10.0,
+        10.0,
+        80.0,
+        40.0,
+    )));
+    doc.add_element(Element::Ellipse(ShapeElement::new(
+        "ell-1".into(),
+        120.0,
+        10.0,
+        60.0,
+        60.0,
+    )));
+    doc.add_element(Element::Diamond(ShapeElement::new(
+        "dia-1".into(),
+        10.0,
+        80.0,
+        60.0,
+        60.0,
+    )));
+    doc.add_element(Element::Line(LineElement::new(
+        "line-1".into(),
+        120.0,
+        80.0,
+        vec![Point::new(0.0, 0.0), Point::new(40.0, 40.0)],
+    )));
+    doc.add_element(Element::Arrow(LineElement::new(
+        "arr-1".into(),
+        10.0,
+        160.0,
+        vec![Point::new(0.0, 0.0), Point::new(60.0, 0.0)],
+    )));
+    doc.add_element(Element::FreeDraw(FreeDrawElement::new(
+        "fd-1".into(),
+        120.0,
+        160.0,
+        vec![
+            Point::new(0.0, 0.0),
+            Point::new(10.0, 15.0),
+            Point::new(25.0, 5.0),
+        ],
+    )));
+    doc.add_element(Element::Text(TextElement::new(
+        "txt-1".into(),
+        10.0,
+        240.0,
+        "hello draw".into(),
+    )));
+    doc
+}
+
+#[test]
+fn full_pipeline_all_element_types() {
+    let doc = populated_doc("full pipeline");
+    assert_eq!(doc.elements.len(), 7);
+
+    // JSON round-trip preserves structure
+    let json = serde_json::to_string(&doc).expect("serialize");
+    let loaded: Document = serde_json::from_str(&json).expect("deserialize");
+    assert_eq!(doc, loaded);
+
+    // SVG export is well-formed and mentions every element we put in
+    let svg = export_svg(&doc);
+    assert!(svg.starts_with("<svg"));
+    assert!(svg.ends_with("</svg>"));
+    // Each element type produces at least one of its SVG primitive
+    assert!(svg.contains("<rect"), "rectangle missing: {svg}");
+    assert!(svg.contains("<ellipse"), "ellipse missing: {svg}");
+    assert!(svg.contains("<polygon"), "diamond missing: {svg}");
+    assert!(svg.contains("<path"), "line/arrow/freedraw missing: {svg}");
+    assert!(svg.contains("<text"), "text missing: {svg}");
+
+    // PNG export produces a valid PNG (magic bytes present)
+    let png = export_png(&doc).expect("png export");
+    assert!(png.starts_with(&[0x89, b'P', b'N', b'G']), "bad PNG header");
+}
+
+#[test]
+fn file_save_load_roundtrip_preserves_everything() {
+    use draw_core::storage;
+
+    let doc = populated_doc("save load");
+    let dir = tempfile::tempdir().unwrap();
+    let path = dir.path().join("drawing.draw.json");
+
+    storage::save(&doc, &path).expect("save");
+    let loaded = storage::load(&path).expect("load");
+
+    assert_eq!(doc, loaded);
+}
+
+#[test]
+fn arrow_bindings_roundtrip_via_serde() {
+    // Bindings were added in #35 but have no inline test coverage.
+    let mut arrow = LineElement::new(
+        "a1".into(),
+        0.0,
+        0.0,
+        vec![Point::new(0.0, 0.0), Point::new(100.0, 0.0)],
+    );
+    arrow.start_binding = Some(Binding {
+        element_id: "rect-a".into(),
+        focus: 0.25,
+        gap: 4.0,
+    });
+    arrow.end_binding = Some(Binding {
+        element_id: "rect-b".into(),
+        focus: -0.5,
+        gap: 8.0,
+    });
+
+    let mut doc = Document::new("bindings".into());
+    doc.add_element(Element::Arrow(arrow));
+
+    let json = serde_json::to_string(&doc).unwrap();
+    let loaded: Document = serde_json::from_str(&json).unwrap();
+    assert_eq!(doc, loaded);
+
+    let Element::Arrow(restored) = &loaded.elements[0] else {
+        panic!("expected Arrow variant after round-trip");
+    };
+    let start = restored.start_binding.as_ref().expect("start_binding");
+    assert_eq!(start.element_id, "rect-a");
+    assert_eq!(start.focus, 0.25);
+    assert_eq!(start.gap, 4.0);
+    let end = restored.end_binding.as_ref().expect("end_binding");
+    assert_eq!(end.element_id, "rect-b");
+    assert_eq!(end.focus, -0.5);
+    assert_eq!(end.gap, 8.0);
+}
+
+#[test]
+fn bindings_default_to_none_on_legacy_docs() {
+    // A LineElement serialized before bindings existed should still deserialize.
+    let legacy_json = r#"{
+        "id": "test",
+        "version": 1,
+        "name": "legacy",
+        "elements": [{
+            "type": "Arrow",
+            "id": "a1",
+            "x": 0.0,
+            "y": 0.0,
+            "points": [{"x": 0.0, "y": 0.0}, {"x": 10.0, "y": 0.0}]
+        }],
+        "created_at": "2026-01-01T00:00:00Z",
+        "modified_at": "2026-01-01T00:00:00Z"
+    }"#;
+    let doc: Document = serde_json::from_str(legacy_json).expect("legacy parse");
+    let Element::Arrow(line) = &doc.elements[0] else {
+        panic!("expected Arrow");
+    };
+    assert!(line.start_binding.is_none());
+    assert!(line.end_binding.is_none());
+}
+
+#[test]
+fn element_helpers_dispatch_across_all_variants() {
+    // Exercises Element::id() / position() / set_position() / opacity() /
+    // is_locked() / group_id() for every variant via the public API.
+    let mut doc = populated_doc("helpers");
+    for element in &mut doc.elements {
+        let original_id = element.id().to_string();
+        let (x, y) = element.position();
+        element.set_position(x + 5.0, y + 5.0);
+        let (nx, ny) = element.position();
+        assert_eq!(nx, x + 5.0, "{original_id} x did not move");
+        assert_eq!(ny, y + 5.0, "{original_id} y did not move");
+        assert_eq!(element.opacity(), 1.0);
+        assert!(!element.is_locked());
+        assert!(element.group_id().is_none());
+    }
+}
+
+#[test]
+fn empty_document_exports_safely() {
+    let doc = Document::new("empty".into());
+    let svg = export_svg(&doc);
+    assert!(svg.contains("<svg"));
+    assert!(svg.contains("</svg>"));
+    let png = export_png(&doc).expect("png of empty doc");
+    assert!(png.starts_with(&[0x89, b'P', b'N', b'G']));
+}