fix: Respecting max/min opacities, and adding tests. (apache#20555)

* Respecting max/min opacities, and adding tests.

* revising tests

* Adding missing test case for maximum coverage :)

* removing unnecessary logic and test

* adding another unit test for (hopefully) full coverage.

* no more ternary operator

* New approach with Math.min  - take THAT codecov.

* one more stab at making codecov happy... ignoring the file next.

* lint fixes

superset-frontend/packages/superset-ui-chart-controls/src/utils/getColorFormatters.ts

@@ -37,16 +37,21 @@ export const getOpacity = (
   extremeValue: number,
   minOpacity = MIN_OPACITY_BOUNDED,
   maxOpacity = MAX_OPACITY,
-) =>
-  extremeValue === cutoffPoint
-    ? maxOpacity
-    : round(
-        Math.abs(
-          ((maxOpacity - minOpacity) / (extremeValue - cutoffPoint)) *
-            (value - cutoffPoint),
-        ) + minOpacity,
-        2,
-      );
+) => {
+  if (extremeValue === cutoffPoint) {
+    return maxOpacity;
+  }
+  return Math.min(
+    maxOpacity,
+    round(
+      Math.abs(
+        ((maxOpacity - minOpacity) / (extremeValue - cutoffPoint)) *
+          (value - cutoffPoint),
+      ) + minOpacity,
+      2,
+    ),
+  );
+};
 
 export const getColorFunction = (
   {

superset-frontend/packages/superset-ui-chart-controls/test/utils/getColorFormatters.test.ts

@@ -50,6 +50,9 @@ describe('getOpacity', () => {
     expect(getOpacity(100, 100, 50)).toEqual(0.05);
     expect(getOpacity(100, 100, 100, 0, 0.8)).toEqual(0.8);
     expect(getOpacity(100, 100, 50, 0, 1)).toEqual(0);
+    expect(getOpacity(999, 100, 50, 0, 1)).toEqual(1);
+    expect(getOpacity(100, 100, 50, 0.99, 1)).toEqual(0.99);
+    expect(getOpacity(99, 100, 50, 0, 1)).toEqual(0.02);
   });
 });