feat: initial Signage 0.1.0

tests/support/images.ts

@@ -0,0 +1,80 @@
+import sharp from "sharp";
+
+/** Real encoded images, generated rather than checked in, so a fixture can never drift from what the
+ * pipeline actually accepts. */
+export async function makeImage(options: {
+  readonly width: number;
+  readonly height: number;
+  readonly format: "png" | "jpeg" | "webp";
+  readonly alpha?: boolean;
+  readonly colour?: { r: number; g: number; b: number };
+}): Promise<Uint8Array> {
+  const colour = options.colour ?? { b: 40, g: 120, r: 200 };
+  const pipeline = sharp({
+    create: {
+      background: { ...colour, alpha: options.alpha === true ? 0.5 : 1 },
+      channels: options.alpha === true ? 4 : 3,
+      height: options.height,
+      width: options.width,
+    },
+  });
+  const encoded =
+    options.format === "png"
+      ? await pipeline.png().toBuffer()
+      : options.format === "jpeg"
+        ? await pipeline.jpeg().toBuffer()
+        : await pipeline.webp().toBuffer();
+  return new Uint8Array(encoded);
+}
+
+/** A genuine two-frame animated WebP. Signage refuses animation: a signage slide is a still frame,
+ * and an animated one would loop out of step with the authoritative slot deadline. */
+export async function makeAnimatedWebp(): Promise<Uint8Array> {
+  const frame = (red: number) =>
+    sharp({
+      create: { background: { alpha: 1, b: 0, g: 0, r: red }, channels: 4, height: 8, width: 8 },
+    })
+      .raw()
+      .toBuffer();
+  const frames = Buffer.concat([await frame(255), await frame(0)]);
+  const encoded = await sharp(frames, {
+    raw: { channels: 4, height: 16, pageHeight: 8, width: 8 },
+  })
+    .webp({ delay: [100, 100], loop: 0 })
+    .toBuffer();
+  return new Uint8Array(encoded);
+}
+
+/** A genuine two-frame animated GIF. GIF is refused outright, but animation is detected first, so
+ * this proves the *animation* rule rather than the format rule. */
+export async function makeAnimatedGif(): Promise<Uint8Array> {
+  const frame = (red: number) =>
+    sharp({
+      create: { background: { alpha: 1, b: 0, g: 0, r: red }, channels: 4, height: 8, width: 8 },
+    })
+      .raw()
+      .toBuffer();
+  const frames = Buffer.concat([await frame(255), await frame(0)]);
+  const encoded = await sharp(frames, {
+    raw: { channels: 4, height: 16, pageHeight: 8, width: 8 },
+  })
+    .gif({ delay: [100, 100], loop: 0 })
+    .toBuffer();
+  return new Uint8Array(encoded);
+}
+
+export function bytesOf(value: string): Uint8Array {
+  return new TextEncoder().encode(value);
+}
+
+/** A minimal, genuinely well-formed SVG. Signage refuses it: an SVG is a document with script and
+ * external-reference capability, not a raster image. */
+export const SVG_DOCUMENT =
+  '<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><rect width="10" height="10"/></svg>';
+
+/** The first bytes of a PDF. Refused for the same reason as everything else that is not a still
+ * raster image. */
+export const PDF_DOCUMENT = "%PDF-1.7\n1 0 obj<</Type/Catalog>>endobj\ntrailer<</Root 1 0 R>>";
+
+/** A GIF89a header with one tiny frame. */
+export const GIF_DOCUMENT_BASE64 = "R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7";