Support changing null to false in update-bcd

Fixes #1042.

scripts/update-bcd.test.ts

@@ -893,6 +893,33 @@ describe("BCD updater", () => {
  );
  });
 
+ it("detects updates in statements with null values", () => {
+ // Both a true and false test result is new information, but null is not.
+ assert.isTrue(
+ hasSupportUpdates(new Map([["80", true]]), [
+ {
+ version_added: null,
+ },
+ ]),
+ );
+
+ assert.isTrue(
+ hasSupportUpdates(new Map([["80", false]]), [
+ {
+ version_added: null,
+ },
+ ]),
+ );
+
+ assert.isFalse(
+ hasSupportUpdates(new Map([["80", null]]), [
+ {
+ version_added: null,
+ },
+ ]),
+ );
+ });
+
  it("detects updates in statements with boolean values", () => {
  assert.isFalse(
  hasSupportUpdates(new Map([["80", false]]), [

scripts/update-bcd.ts

@@ -819,14 +819,18 @@ const skipCurrentBeforeSupport = skip("currentBeforeSupport", ({
  * @param version - A version string.
  * @param hasSupport - An boolean indicating if a test result for the version shows support.
  * @param statements - An array of default statements.
- * @returns A boolean indicating whether default statements indicate support for the version.
+ * @returns A boolean or null indicating whether default statements indicate support for the version.
  */
 const isSupported = (
  version: string,
  hasSupport: boolean,
  statements: SimpleSupportStatement[],
 ) => {
  for (const {version_added, version_removed} of statements) {
+ if (version_added === null) {
+ return null;
+ }
+
  if (version_added === "preview") {
  return false;
  }
@@ -858,7 +862,7 @@ const isSupported = (
  * Iterates through a BrowserSupportMap and checks each version for possible updates against a set of default statements.
  * @param versionMap - A map of versions and support assertions.
  * @param defaultStatements - An array of default statements.
- * @returns A boolean indicating whether possible updates to the default statments have been detected.
+ * @returns A boolean indicating whether possible updates to the default statements have been detected.
  */
 export const hasSupportUpdates = (
  versionMap: BrowserSupportMap,