chore: establish Strategy Lab source baseline (development, not release)

1 files changed, 36 insertions, 0 deletions

diff --git a/frontend/src/test-setup.ts b/frontend/src/test-setup.ts
new file mode 100644
index 0000000..cdd6071
--- /dev/null
+++ b/frontend/src/test-setup.ts
@@ -0,0 +1,36 @@
+
+// jsdom does not implement Range.getClientRects, which CodeMirror's
+// measurement layer calls for drawing decorations (diagnostics markers).
+// Without it the suite emits an unhandled
+// `textRange(...).getClientRects is not a function` TypeError even though
+// assertions pass. Narrow geometry shim ONLY for the missing API; it returns
+// one empty rect, from which CodeMirror derives null geometry — no other
+// errors are suppressed.
+if (typeof Range !== 'undefined' && !Range.prototype.getClientRects) {
+  const EMPTY_RECT = { left: 0, right: 0, top: 0, bottom: 0, width: 0, height: 0, x: 0, y: 0, toJSON() { return {}; } };
+  Range.prototype.getClientRects = function getClientRects() {
+    return [EMPTY_RECT] as unknown as DOMRectList;
+  };
+}
+
+// jsdom ships no canvas backend: HTMLCanvasElement.prototype.getContext exists
+// but throws "Not implemented". Charts render with ECharts' SVG renderer; the
+// only canvas user in tests is zrender's text-metrics helper (measureText
+// paints into a hidden canvas). Replace getContext ONLY when the native
+// implementation is the throwing stub, and provide just the measurement
+// approximation — SVG chart rendering itself (the part regressions inspect)
+// is untouched and fully real.
+if (typeof HTMLCanvasElement !== 'undefined') {
+    HTMLCanvasElement.prototype.getContext = function getContext(this: HTMLCanvasElement, contextId: string) {
+      if (contextId === '2d') {
+        return {
+          canvas: this,
+          font: '',
+          measureText(text: string) {
+            return { width: String(text).length * 7, actualBoundingBoxAscent: 7, actualBoundingBoxDescent: 1 };
+          }
+        } as unknown as CanvasRenderingContext2D;
+      }
+      return null;
+    } as unknown as typeof HTMLCanvasElement.prototype.getContext;
+}