Add --diverge-at option to allow specification of where branches diverge from main

Signed-off-by: Jacob Stopak <[email protected]>

Author: initialcommit-io

README.md

@@ -7,11 +7,11 @@
 
 Generate dummy Git repositories and populate them with the desired number of commits, branches, and structure.
 
-Example: `$ git-dummy --commits=10 --branches=2`
+Example: `$ git-dummy --commits=10 --branches=2 --diverge-at=3`
 
 This will initialize a new Git repo in the current directory with 2 branches, each containing 10 commits.
 
-Note: All generated dummy repos have at minimum 1 branch called `main`. For dummies with multiple branches, branches are named `branch1, branch2, ..., branchN`. Each branch currently branches off of `main` at a randomly chosen commit. The length of each branch is capped at the number of commits specified by `--commits`.
+Note: All generated dummy repos have at minimum 1 branch called `main`. For dummies with multiple branches, branches are named `branch1, branch2, ..., branchN`. Each branch currently branches off of `main` at `--diverge-at` if supplied, or else a randomly chosen commit. The length of each branch is capped at the number of commits specified by `--commits`.
 
 ## Use cases
 - Programatically generate Git repos for functional testing of Git tools
@@ -61,6 +61,7 @@ Available options and flags include:
 `--name`: The name of the dummy Git repo, defaults to "dummy".  
 `--commits`: The number of commits to populate in the dummy Git repo, defaults to 5.  
 `--branches`: The number of branches to generate in the dummy Git repo, defaults to 1.  
+`--diverge-at`: The commit number at which branches diverge from `main`.
 `--git-dir`: The path at which to store the dummy Git repo, defaults to current directory.
 
 ## Command examples
@@ -70,6 +71,12 @@ Generate a dummy Git repo called "cheese" on your Desktop, with 2 branches and 1
 $ git-dummy --name=cheese --branches=2 --commits=10 --git-dir=~/Desktop
 ```
 
+Generate a dummy repo with 4 branches `main`, `branch1`, `branch2`, and `branch3`. Branches diverge from `main` after the 2nd commit:
+
+```console
+$ git-dummy --branches=4 --diverge-at=2
+```
+
 For convenience, environment variables can be set for any command-line option available in git-dummy. All environment variables start with `git_dummy_` followed by the name of the option.
 
 For example, the `--git-dir` option can be set as an environment variable like:

git_dummy/__main__.py

@@ -27,11 +27,16 @@ def main(
         settings.branches,
         help="The number of branches to generate",
     ),
+    diverge_at: int = typer.Option(
+        settings.diverge_at,
+        help="The point branches diverge from main at",
+    ),
 ):
     settings.name = name
     settings.git_dir = os.path.join(os.path.expanduser(git_dir), name)
     settings.commits = commits
     settings.branches = branches
+    settings.diverge_at = diverge_at
 
     repo = git.Repo.init(settings.git_dir)
     repo.config_writer().set_value("init", "defaultBranch", "main").release()
@@ -43,7 +48,11 @@ def main(
 
     while settings.branches - 1 > 0:
         repo.git.checkout("main")
-        r = random.choice(range(1, settings.commits))
+        r = (
+            (settings.commits - settings.diverge_at)
+            if settings.diverge_at
+            else random.choice(range(1, settings.commits))
+        )
         repo.git.checkout(f"HEAD~{r}")
         branch_name = f"branch{settings.branches - 1}"
         repo.create_head(branch_name)

git_dummy/settings.py

@@ -7,6 +7,7 @@ class Settings(BaseSettings):
     git_dir = pathlib.Path().cwd()
     commits = 5
     branches = 1
+    diverge_at = 0
 
     class Config:
         env_prefix = "git_dummy_"