Sprout Method example

BlogPostPublisher.ts

//////////////////////////////////////////////////
// Step 1: Identify the change point and determine the sprouted method signature (input/output)

export class BlogPostPublisher {
    private blogActivityRecord: BlogActivityRecord;
    private entriesRepository: EntriesRepository;

    constructor(blogActivityRecord: BlogActivityRecord) {
        this.blogActivityRecord = blogActivityRecord;
        this.entriesRepository = new MySqlEntriesRepository();
    }

    public postEntries(): void {
        const entries = this.entriesRepository.getAll();
        // <-- this is the change point
        for (const entry of entries) {
            entry.post();
        }

        this.blogActivityRecord.add(entries);
    }
}
               
//////////////////////////////////////////////////
// Step 2: Develop the sprouted method with tests 

export class BlogPostPublisher {
    // rest of the code omitted for brevity...

    public postEntries(): void {
        // rest of the code omitted for brevity...
    }

    // the sprouted method
    public uniqueEntries(entries: Entry[]): Entry[] {
        const result: Entry[] = [];
        for (const entry of entries) {
            if (!this.blogActivityRecord.contains(entry)) {
                result.push(entry);
            }
        }
        return result;
    }
}

////////////////////////////////////////////////////
// Step 3: Call the sprouted method from the source method

export class BlogPostPublisher {
    // rest of the code omitted for brevity...

    public postEntries(): void {
        const allEntries = this.entriesRepository.getAll();
        const entries = this.uniqueEntries(allEntries); // <-- call to the sprouted method
        for (const entry of entries) {
            entry.post();
        }

        this.blogActivityRecord.add(entries);
    }

    public uniqueEntries(entries: Entry[]): Entry[] {
        const result: Entry[] = [];
        for (const entry of entries) {
            if (!this.blogActivityRecord.contains(entry)) {
                result.push(entry);
            }
        }
        return result;
    }
}