fix(autoreplace): handle digest-only update without replaceString

lib/workers/repository/update/branch/auto-replace.spec.ts

@@ -263,7 +263,7 @@ describe('workers/repository/update/branch/auto-replace', () => {
       await expect(res).rejects.toThrow(WORKER_FILE_UPDATE_FAILED);
     });
 
-    it('fails with digest mismatch', async () => {
+    it('updates digest when only digest changes and no replaceString is set', async () => {
       const dockerfile = codeBlock`
         FROM java:11@sha256-1234 as build
       `;
@@ -277,8 +277,8 @@ describe('workers/repository/update/branch/auto-replace', () => {
       upgrade.newValue = '11';
       upgrade.newDigest = 'sha256-5678';
       upgrade.packageFile = 'Dockerfile';
-      const res = doAutoReplace(upgrade, dockerfile, reuseExistingBranch);
-      await expect(res).rejects.toThrow(WORKER_FILE_UPDATE_FAILED);
+      const res = await doAutoReplace(upgrade, dockerfile, reuseExistingBranch);
+      expect(res).toBe('FROM java:11@sha256-5678 as build');
     });
 
     it('updates with docker replacement', async () => {
@@ -1430,6 +1430,30 @@ describe('workers/repository/update/branch/auto-replace', () => {
       );
     });
 
+    it('jsonata: update currentDigest with currentValue captured', async () => {
+      const source =
+        '[ { "version": "1.2.3", "digest": "abcdef", "package": "foo" } ]';
+      upgrade.manager = 'jsonata';
+      upgrade.depName = 'foo';
+      upgrade.currentValue = '1.2.3';
+      upgrade.currentDigest = 'abcdef';
+      upgrade.newDigest = 'badbeef';
+      upgrade.depIndex = 0;
+      upgrade.packageFile = 'deps.json';
+      // @ts-expect-error -- TODO: improve typing
+      upgrade.fileFormat = 'json';
+      // @ts-expect-error -- TODO: improve typing
+      upgrade.datasourceTemplate = 'github-releases';
+      // @ts-expect-error -- TODO: improve typing
+      upgrade.matchStrings = [
+        '*.{"depName": package, "currentDigest": digest, "currentValue": version }',
+      ];
+      const res = await doAutoReplace(upgrade, source, reuseExistingBranch);
+      expect(res).toBe(
+        '[ { "version": "1.2.3", "digest": "badbeef", "package": "foo" } ]',
+      );
+    });
+
     it('github-actions: updates with newValue only', async () => {
       const githubAction = codeBlock`
         jobs:

lib/workers/repository/update/branch/auto-replace.ts

@@ -197,28 +197,6 @@ async function checkExistingBranch(
   return existingContent;
 }
 
-/**
- * Check if an update from `current` to `newString` should be performed and return 1 if so.
- *
- * @remarks
- * Useful for counting the number of updates to do.
- *
- * @param current The current value (if undefined then no update is required)
- * @param newString The new value (if undefined then no update is required)
- *
- * @returns 1 if `current !== newString` and 0 if they are equal or at least one is undefined.
- */
-function updatedToInt(
-  current: string | undefined | null,
-  newString: string | undefined | null,
-): number {
-  if (current && newString && newString !== current) {
-    return 1;
-  } else {
-    return 0;
-  }
-}
-
 export async function doAutoReplace(
   upgrade: BranchUpgradeConfig,
   existingContent: string,
@@ -247,27 +225,31 @@ export async function doAutoReplace(
   if (reuseExistingBranch) {
     return await checkExistingBranch(upgrade, existingContent);
   }
-
-  // count how many strings need to be updated
-  const changedCount =
-    updatedToInt(depName, newName) +
-    updatedToInt(currentValue, newValue) +
-    updatedToInt(currentDigest, newDigest);
-  if (changedCount > 1) {
-    logger.debug(
-      { packageFile, depName, changedCount },
-      'Multiple changed values, might need special handling (#36461)',
-    );
+  const valueChanging =
+    isString(currentValue) && isString(newValue) && currentValue !== newValue;
+  const digestChanging =
+    isString(currentDigest) &&
+    isString(newDigest) &&
+    currentDigest !== newDigest;
+  let replaceWithoutReplaceString =
+    isString(newName) &&
+    newName !== depName &&
+    (isUndefined(upgrade.replaceString) ||
+      !upgrade.replaceString?.includes(depName!));
+  // fallback must contain the field being updated, else the replacement is
+  // a no-op for managers where value and digest live in separate tokens
+  let replaceString = upgrade.replaceString;
+  if (isUndefined(replaceString)) {
+    if (valueChanging && digestChanging) {
+      // no single fallback covers both — use the per-field path
+      replaceWithoutReplaceString = true;
+      replaceString = currentValue;
+    } else if (digestChanging) {
+      replaceString = currentDigest;
+    } else {
+      replaceString = currentValue ?? currentDigest;
+    }
   }
-
-  const replaceWithoutReplaceString =
-    (isString(newName) &&
-      newName !== depName &&
-      (isUndefined(upgrade.replaceString) ||
-        !upgrade.replaceString?.includes(depName!))) ||
-    // for jsonata manager, fixes #36461
-    (isUndefined(upgrade.replaceString) && changedCount > 1);
-  const replaceString = upgrade.replaceString ?? currentValue ?? currentDigest;
   logger.trace({ depName, replaceString }, 'autoReplace replaceString');
   let searchIndex: number;
   if (replaceWithoutReplaceString) {