test: add tests to setBlendedVisiblePixel

Author: EscapedGibbon

src/utils/__tests__/setBlendedVisiblePixel.test.ts

@@ -0,0 +1,63 @@
+import { setBlendedVisiblePixel } from '../setBlendedVisiblePixel';
+
+test('GREYA image, default options', () => {
+  const image = testUtils.createGreyaImage([
+    [50, 255],
+    [20, 30],
+  ]);
+  setBlendedVisiblePixel(image, 0, 1);
+  expect(image).toMatchImageData([
+    [50, 255],
+    [0, 255],
+  ]);
+});
+
+test('GREYA image: set pixel out of bounds', () => {
+  const image = testUtils.createGreyaImage([
+    [50, 255, 1, 2, 3, 4],
+    [20, 30, 5, 6, 7, 8],
+    [1, 2, 3, 4, 5, 6],
+  ]);
+  setBlendedVisiblePixel(image, 0, 5, { color: [40, 40] });
+  expect(image).toMatchImageData([
+    [50, 255, 1, 2, 3, 4],
+    [20, 30, 5, 6, 7, 8],
+    [1, 2, 3, 4, 5, 6],
+  ]);
+});
+
+test('RGBA image: set pixel out of bounds', () => {
+  const image = testUtils.createGreyaImage([
+    [50, 255, 1, 200, 2, 3, 4, 200],
+    [20, 30, 5, 200, 6, 7, 8, 200],
+    [1, 2, 3, 200, 4, 5, 6, 200],
+  ]);
+  setBlendedVisiblePixel(image, 0, 5, { color: [40, 40, 40, 40] });
+  expect(image).toMatchImageData([
+    [50, 255, 1, 200, 2, 3, 4, 200],
+    [20, 30, 5, 200, 6, 7, 8, 200],
+    [1, 2, 3, 200, 4, 5, 6, 200],
+  ]);
+});
+
+test('GREYA image: alpha different from 255', () => {
+  const image = testUtils.createGreyaImage([[50, 64]]);
+  setBlendedVisiblePixel(image, 0, 0, { color: [100, 128] });
+  const alpha = 128 + 64 * (1 - 128 / 255);
+  const component = (100 * 128 + 50 * 64 * (1 - 128 / 255)) / alpha;
+  expect(image).toMatchImageData([[component, alpha]]);
+});
+
+test('asymetrical test', () => {
+  const image = testUtils.createGreyaImage([
+    [50, 255, 1, 2, 3, 4],
+    [20, 30, 5, 6, 7, 8],
+    [1, 2, 3, 4, 5, 6],
+  ]);
+  setBlendedVisiblePixel(image, 2, 0, { color: [0, 125] });
+  expect(image).toMatchImageData([
+    [50, 255, 1, 2, 0, 127],
+    [20, 30, 5, 6, 7, 8],
+    [1, 2, 3, 4, 5, 6],
+  ]);
+});