feat: compare with origin/main by default

README.org

@@ -5,8 +5,30 @@
 
 This is a small tool that helps to list the files you have changed (added/modified/removed) in your git branch.
 
-This can be useful when working with large repositories, as you can run tools on a specific subset of files instead of the entire repository.
-It can be easily integrated into your workflow to streamline your development process.
+** Motivation
+
+The author wrote this tool for a project with very slow tests and tools. A full run took too long for each small change. The author wanted to run the tests and tools only on the files of the current branch.
+
+The tool lists these files:
+
+- the files from the commits since the branch left ~origin/main~
+- the files with uncommitted changes
+- the untracked files
+
+The tool only prints the list. Send the list to another tool:
+
+#+begin_src bash
+$ git-changed -e '**/*.rs' | xargs rustfmt
+#+end_src
+
+** Alternatives
+
+- ~git diff --name-only $(git merge-base origin/main HEAD)~ lists the committed and the uncommitted changes. It does not list the untracked files. Add ~git ls-files --others --exclude-standard~ for those.
+- lint-staged (https://github.com/lint-staged/lint-staged) runs commands on the staged files before a commit. It needs Node.js.
+- lefthook (https://github.com/evilmartians/lefthook) is a git hook manager. It gives ~{staged_files}~ and ~{push_files}~ to the commands. A ~lefthook~ command can also call ~git-changed~.
+- tj-actions/changed-files (https://github.com/tj-actions/changed-files) lists the changed files in GitHub Actions.
+
+~git-changed~ does not run commands and does not manage hooks. It only lists the files, so you can use it in a terminal, in a hook, or in CI.
 
 ** Install with Nix
 
@@ -55,7 +77,9 @@ $ git-changed '*.rs' | xargs rustfmt
 
 *** Default branch
 
-Per default the script uses the ~init.defaultBranch~ if that is configured, and falls back to ~main~, you can override this setting by a command line parameter:
+The tool compares your branch with ~origin/main~. It does not use your local ~main~ branch, because that branch can be old.
+
+To use a different base, give the ~--base~ option:
 
 #+begin_src bash
 $ git-changed --base development
@@ -73,11 +97,7 @@ Or only for the current repository:
 $ git config changed.defaultBranch development
 #+end_src
 
-The value can be any revision. If your local ~main~ is older than the remote one, the tool also lists the files that changed on ~main~ after your local copy. To compare with the remote branch, set:
-
-#+begin_src bash
-$ git config changed.defaultBranch origin/main
-#+end_src
+The value can be any revision, for example a branch, a tag, or ~upstream/main~.
 
 *** Filtering files with glob pattern
 
@@ -101,7 +121,48 @@ Some tools may not handle files that no longer exist. With this option, you can
 $ git-changed -e
 #+end_src
 
-*** A more complex example
+*** Examples
+
+Run only the specs of the branch. A new spec file is in the list before you run ~git add~:
+
+#+begin_src bash
+$ git-changed -e 'spec/**/*_spec.rb' | xargs bundle exec rspec
+#+end_src
+
+Lint the changed files. The ~-e~ option removes the deleted files, so the linter does not fail on a missing file:
+
+#+begin_src bash
+$ git-changed -e -0 '**/*.py' | xargs -0 ruff check
+#+end_src
+
+Run the tests again each time that you save a changed file. entr (https://github.com/eradman/entr) reads the list of files to watch from standard input:
+
+#+begin_src bash
+$ git-changed -e '**/*.rs' | entr -c cargo test
+#+end_src
+
+Open all changed files in the editor:
+
+#+begin_src bash
+$ vim $(git-changed -e)
+#+end_src
+
+Select one changed file with fzf (https://github.com/junegunn/fzf) and open it:
+
+#+begin_src bash
+$ vim "$(git-changed -e | fzf)"
+#+end_src
+
+Run a linter before each push with lefthook. The list contains all the work on the branch, also the work that you did not commit:
+
+#+begin_src yaml
+pre-push:
+  commands:
+    rubocop:
+      run: git-changed -e -0 '**/*.rb' | xargs -0 bundle exec rubocop
+#+end_src
+
+Compare with the ~development~ branch and compile each changed file:
 
 #+begin_src bash
 $ git-changed -0 -b development '**/*.rs' | xargs -0 -n 1 rustc

src/git.rs

@@ -11,8 +11,8 @@ use std::collections::BTreeSet;
 use std::path::Path;
 use std::path::PathBuf;
 
-const CONFIG_PATHS: [&str; 2] = ["changed.defaultBranch", "init.defaultBranch"];
-const DEFAULT_BRANCH: &str = "main";
+const CONFIG_PATH: &str = "changed.defaultBranch";
+const DEFAULT_BRANCH: &str = "origin/main";
 
 pub fn open_repository(directory: &Path) -> Result<Repository> {
     Repository::discover(directory)
@@ -56,18 +56,13 @@ fn canonical(path: &Path) -> Result<PathBuf> {
 fn default_branch(repo: &Repository) -> Result<String> {
     let config = repo.config().context("Cannot read the git config")?;
 
-    for path in CONFIG_PATHS {
-        match config.get_string(path) {
-            Ok(branch) => return Ok(branch),
-            Err(error) if error.code() == ErrorCode::NotFound => continue,
-            Err(error) => {
-                return Err(error)
-                    .with_context(|| format!("Cannot read {path} from the git config"))
-            }
+    match config.get_string(CONFIG_PATH) {
+        Ok(branch) => Ok(branch),
+        Err(error) if error.code() == ErrorCode::NotFound => Ok(DEFAULT_BRANCH.to_string()),
+        Err(error) => {
+            Err(error).with_context(|| format!("Cannot read {CONFIG_PATH} from the git config"))
         }
     }
-
-    Ok(DEFAULT_BRANCH.to_string())
 }
 
 fn committed_changes(repo: &Repository, base: &str) -> Result<Vec<String>> {

tests/features/default.feature

@@ -0,0 +1,43 @@
+Feature: Compare with origin/main by default
+
+  Background: A git repository with a remote branch
+    Given an empty directory
+    When the user executes the command: "git init --initial-branch=main"
+    And the user executes the command: "git config user.name 'John Doe'"
+    And the user executes the command: "git config user.email 'jdoe@example.com'"
+    And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
+
+  Scenario: It displays the commits that are not pushed to origin/main
+    When the user executes the command: "touch README.md"
+    And the user executes the command: "git add README.md"
+    And the user executes the command: "git commit --message 'Adding README'"
+    And the user executes the tool like: "git-changed"
+    Then it succeeds with the following output
+      """
+      README.md
+      """
+
+  Scenario: It ignores an old local main branch
+    When the user executes the command: "git switch --create upstream"
+    And the user executes the command: "touch LICENSE"
+    And the user executes the command: "git add LICENSE"
+    And the user executes the command: "git commit --message 'Adding LICENSE'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main upstream"
+    And the user executes the command: "git switch --create feature"
+    And the user executes the command: "touch README.md"
+    And the user executes the command: "git add README.md"
+    And the user executes the command: "git commit --message 'Adding README'"
+    And the user executes the tool like: "git-changed"
+    Then it succeeds with the following output
+      """
+      README.md
+      """
+
+  Scenario: It fails if origin/main does not exist
+    When the user executes the command: "git update-ref -d refs/remotes/origin/main"
+    And the user executes the tool like: "git-changed"
+    Then it fails with the following error
+      """
+      Cannot find the commit of origin/main: revspec 'origin/main' not found; class=Reference (4); code=NotFound (-3)
+      """

tests/features/empty.feature

@@ -6,6 +6,7 @@ Feature: Empty git repository
     And the user executes the command: "git config user.name 'John Doe'"
     And the user executes the command: "git config user.email 'jdoe@example.com'"
     And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
 
   Scenario: It displays nothing
     When the user executes the tool like: "git-changed"

tests/features/non-empty.feature

@@ -6,6 +6,7 @@ Feature: Non-empty git repository
     And the user executes the command: "git config user.name 'John Doe'"
     And the user executes the command: "git config user.email 'jdoe@example.com'"
     And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
     And the user executes the command: "touch README.md"
     And the user executes the command: "git add README.md"
 
@@ -31,10 +32,11 @@ Feature: Non-empty git repository
         README.md
         """
 
-  Rule: With changes committed on the base branch
+  Rule: With changes pushed to the base branch
 
-    Background: With committed changes
+    Background: With pushed changes
       When the user executes the command: "git commit --message 'Adding README'"
+      And the user executes the command: "git update-ref refs/remotes/origin/main main"
 
     Scenario: It displays nothing if there are no changes
       When the user executes the tool like: "git-changed"

tests/features/output.feature

@@ -6,6 +6,7 @@ Feature: Output
     And the user executes the command: "git config user.name 'John Doe'"
     And the user executes the command: "git config user.email 'jdoe@example.com'"
     And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
     And the user executes the command: "touch c.md a.md e.md b.md d.md"
 
   Scenario: It displays the files in sorted order

tests/features/subdirectory.feature

@@ -6,6 +6,7 @@ Feature: Run the tool in a subdirectory
     And the user executes the command: "git config user.name 'John Doe'"
     And the user executes the command: "git config user.email 'jdoe@example.com'"
     And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
     And the user executes the command: "mkdir src"
     And the user executes the command: "touch README.md src/main.rs"
     And the user executes the command: "git add README.md src/main.rs"

tests/features/untracked.feature

@@ -6,6 +6,7 @@ Feature: Untracked files
     And the user executes the command: "git config user.name 'John Doe'"
     And the user executes the command: "git config user.email 'jdoe@example.com'"
     And the user executes the command: "git commit --allow-empty --message 'Initial commit'"
+    And the user executes the command: "git update-ref refs/remotes/origin/main main"
     And the user executes the command: "mkdir docs"
     And the user executes the command: "touch docs/guide.md"