fix --reverse behavior

Author: ds300

integration-tests/apply-multiple-patches/apply-multiple-patches.sh

@@ -33,6 +33,7 @@ then
 fi
 (>&2 echo "END SNAPSHOT")
 
+
 echo "SNAPSHOT: patch-package only applies the first patch if the second of three is invalid"
 if patch-package
 then

integration-tests/reverse-multiple-patches/__snapshots__/reverse-multiple-patches.test.ts.snap

@@ -26,8 +26,8 @@ left-pad@1.3.0 (3 goodbye) ✔
 END SNAPSHOT"
 `;
 
-exports[`Test reverse-multiple-patches: 03: if one of the patches fails then reverse only ondoes the ones that succeeded 1`] = `
-"SNAPSHOT: if one of the patches fails then reverse only ondoes the ones that succeeded
+exports[`Test reverse-multiple-patches: 03: if one of the patches fails then reverse only undoes the ones that succeeded 1`] = `
+"SNAPSHOT: if one of the patches fails then reverse only undoes the ones that succeeded
 patches/left-pad+1.3.0+003+goodbye.patch
  9: -'use schmorld';
  10: +'goodbye schmorld';

src/applyPatches.ts

@@ -13,7 +13,6 @@ import { join, relative, resolve } from "./path"
 import {
  clearPatchApplicationState,
  getPatchApplicationState,
- PatchState,
  savePatchApplicationState,
 } from "./stateFile"
 
@@ -118,8 +117,8 @@ export function applyPatchesForApp({
  )) {
  const state =
  patches.length > 1 ? getPatchApplicationState(patches[0]) : null
- let unappliedPatches = patches.slice(0)
- const newState: PatchState[] | null = patches.length > 1 ? [] : null
+ const unappliedPatches = patches.slice(0)
+ const appliedPatches: PatchedPackageDetails[] = []
  // if there are multiple patches to apply, we can't rely on the reverse-patch-dry-run behavior to make this operation
  // idempotent, so instead we need to check the state file to see whether we have already applied any of the patches
  // todo: once this is battle tested we might want to use the same approach for single patches as well, but it's not biggie since the dry run thing is fast
@@ -132,7 +131,7 @@ export function applyPatchesForApp({
  )
  if (patchThatWasApplied.patchContentHash === currentPatchHash) {
  // this patch was applied we can skip it
- unappliedPatches.shift()
+ appliedPatches.push(unappliedPatches.shift()!)
  } else {
  console.error(
  chalk.red("Error:"),
@@ -144,14 +143,21 @@ export function applyPatchesForApp({
  }
  }
 
- if (reverse) {
- unappliedPatches = patches
- .slice(0, patches.length - unappliedPatches.length)
- .reverse()
+ if (reverse && state) {
+ // if we are reversing the patches we need to make the unappliedPatches array
+ // be the reversed version of the appliedPatches array.
+ // The applied patches array should then be empty because it is used differently
+ // when outputting the state file.
+ unappliedPatches.length = 0
+ unappliedPatches.push(...appliedPatches)
+ unappliedPatches.reverse()
+ appliedPatches.length = 0
  }
- if (unappliedPatches.length === 0) {
+ if (appliedPatches.length) {
  // all patches have already been applied
- patches.forEach(logPatchApplication)
+ appliedPatches.forEach(logPatchApplication)
+ }
+ if (!unappliedPatches.length) {
  continue
  }
  packageLoop: for (const patchDetails of unappliedPatches) {
@@ -191,11 +197,7 @@ export function applyPatchesForApp({
  cwd: process.cwd(),
  })
  ) {
- newState?.push({
- patchFilename,
- patchContentHash: hashFile(join(appPath, patchDir, patchFilename)),
- didApply: true,
- })
+ appliedPatches.push(patchDetails)
  // yay patch was applied successfully
  // print warning if version mismatch
  if (installedPackageVersion !== version) {
@@ -256,11 +258,53 @@ export function applyPatchesForApp({
  }
  }
 
- if (newState) {
+ if (patches.length > 1) {
  if (reverse) {
- clearPatchApplicationState(patches[0])
+ if (!state) {
+ throw new Error(
+ "unexpected state: no state file found while reversing",
+ )
+ }
+ // if we removed all the patches that were previously applied we can delete the state file
+ if (appliedPatches.length === patches.length) {
+ clearPatchApplicationState(patches[0])
+ } else {
+ // We failed while reversing patches and some are still in the applied state.
+ // We need to update the state file to reflect that.
+ // appliedPatches is currently the patches that were successfully reversed, in the order they were reversed
+ // So we need to find the index of the last reversed patch in the original patches array
+ // and then remove all the patches after that. Sorry for the confusing code.
+ const lastReversedPatchIndex = patches.indexOf(
+ appliedPatches[appliedPatches.length - 1],
+ )
+ if (lastReversedPatchIndex === -1) {
+ throw new Error(
+ "unexpected state: failed to find last reversed patch in original patches array",
+ )
+ }
+
+ savePatchApplicationState(
+ patches[0],
+ patches.slice(0, lastReversedPatchIndex).map((patch) => ({
+ didApply: true,
+ patchContentHash: hashFile(
+ join(appPath, patchDir, patch.patchFilename),
+ ),
+ patchFilename: patch.patchFilename,
+ })),
+ )
+ }
  } else {
- savePatchApplicationState(patches[0], newState)
+ savePatchApplicationState(
+ patches[0],
+ appliedPatches.map((patch) => ({
+ didApply: true,
+ patchContentHash: hashFile(
+ join(appPath, patchDir, patch.patchFilename),
+ ),
+ patchFilename: patch.patchFilename,
+ })),
+ )
  }
  }
  }