ng update @my/lib@version - Which migration schematics will be executed? 🤷

The command ng update @my/lib@version downloads the specified version of the library and launches all schematics listed in its migrations.json that have an appropriate property of "version" within the semver range from >installedVersion to <=targetVersion.

Example

For instance, consider the following conditions:

• The locally installed version of @my/lib in my project is 1.1.0.
• The latest published npm version of @my/lib is 4.8.9.
• Now, when we run ng update @my/lib (or ...@my/lib@4 or ...@my/lib@4.8 or ...@my/lib@4.8.9, it doesn't matter),
• and the file migration.json of @my/lib contains migrations for the "version" 2.0.0 and 4.5.0:

{
  "schematics": {
    "migration-v2": {
      "version": "2.0.0",
      "factory": "./migration-v2#migrate",
      "description": "Migration for v2.0.0"
    },
    "migration-v4.5": {
      "version": "4.5.0",
      "factory": "./migration-v4_5#migrate",
      "description": "Migration for v4.5.0"
    },
  }
}

...then the following migrations will be executed, in ascending order of version:

• Migration for v2.0.0
• Migration for v4.5.0

This is because they fall between the currently installed version (>1.1.0) and the target version (<=4.8.9).

Note: If we were to run ng update @my/lib@ with the target version lower than 4.5.0, for example, ng update @my/lib@3, only the following migration would be executed:

• Migration for v2.0.0

However, the Migration for v4.5.0 would not run.

Angular CLI source code analysis

Here's a proof in the source code of the Angular CLI:

• If the "version" field from migrations.json belongs to the appropriate semver range, then this migration is launched (see source).

• The appropriate semver range means something between >fromVersion and <=toVersion (see sources: executeMigration() and invocation of executeMigration()).

• The fromVersion and toVersion respectively mean: installed.version and target.version (see source).

Therefore, all migrations between >installed.version and <=target.version are launched.