fix: preserve migration headers after failed commit

.changeset/fruity-guests-take.md

@@ -0,0 +1,6 @@
+---
+"graphile-migrate": patch
+---
+
+Fix a bug when commit fails: restore the original migration fully (don't drop
+`Message` header)

__tests__/commit.test.ts

@@ -29,6 +29,20 @@ it("aborts if current.sql is empty", async () => {
   );
 });
 
+it("restores migration headers after a failed commit", async () => {
+  const original = "--! Message: test-migration\n\nselect 1 + ;\n";
+  mockFs({
+    "migrations/current.sql": original,
+  });
+
+  await expect(commit(settings)).rejects.toThrow();
+
+  expect(await fsp.readFile("migrations/current.sql", "utf8")).toEqual(
+    original,
+  );
+  expect(await fsp.readdir("migrations/committed")).toEqual([]);
+});
+
 describe.each([[undefined], ["My Commit Message"]])(
   "commit message '%s'",
   (commitMessage) => {

src/commands/commit.ts

@@ -119,7 +119,7 @@ export async function _commit(
     logDbError(parsedSettings, e);
 
     parsedSettings.logger.error("ABORTING...");
-    await writeCurrentMigration(parsedSettings, currentLocation, body);
+    await writeCurrentMigration(parsedSettings, currentLocation, contents);
     await fsp.unlink(newMigrationFilepath);
     parsedSettings.logger.error("ABORTED AND ROLLED BACK");
     throw e;