refactoring-safely

Safe refactoring preserves behavior by running your full test suite before and after each small change. Make one tiny transformation—extract a method, rename a variable, or reorganize a module—then verify tests still pass before committing. This change-test-commit cycle ensures you're restructuring, not rewriting.

Yes. Incremental refactoring works best with automated test suites already in place. Break the refactoring into single, focused tasks—extracting duplicate logic, renaming identifiers, or moving structure—completing each with a test run and commit before starting the next.

Apply one transformation at a time: extract the method or rename the identifier, run the full test suite immediately, then commit with a clear message describing the change. Repeat this cycle for each refactoring task until complete, keeping tests green throughout.

Tests that stay green throughout refactoring prove behavior hasn't changed. If a test fails mid-refactor, you've crossed into rewriting rather than restructuring. Green tests at every step guarantee the refactored code is functionally equivalent to the original.

Yes. Safe refactoring requires automated tests covering the code you're restructuring. Without a test suite, you cannot verify that changes preserve behavior, so you risk introducing bugs while reorganizing modules or extracting logic.