Add an option for running elvis git-branch BRANCH|SHA. Similar to g…

…it-hook but instead takes all changes since BRANCH or SHA

- Minor cleanup in git_SUITE

src/elvis.erl

@@ -115,6 +115,9 @@ process_commands(['install', 'git-hook' | Cmds], Config) ->
 process_commands(['git-hook' | Cmds], Config) ->
     elvis_git:run_hook(Config),
     process_commands(Cmds, Config);
+process_commands(['git-branch', Branch | Cmds], Config) ->
+    elvis_git:run_branch(atom_to_list(Branch), Config),
+    process_commands(Cmds, Config);
 process_commands([], _Config) ->
     ok;
 process_commands([_Cmd | _Cmds], _Config) ->
@@ -142,6 +145,11 @@ rock [file...]   Rock your socks off by running all rules to your source files.
 git-hook         Pre-commit Git Hook: Gets all staged files and runs the rules
                                       specified in the configuration to those
                                       files.
+
+git-branch [branch|sha]
+                 Rock your socks off by running all rules on source files that
+                 have changed since branch or sha.
+
 install git-hook
                 Installs Elvis as a pre-commit hook in your current working
                 directory, which should be a git repository.

src/elvis_git.erl

@@ -2,7 +2,9 @@
 
 -export([
          run_hook/1,
+         run_branch/2,
          staged_files/0,
+         branch_files/1,
          staged_content/1,
          relative_position/2,
          install_hook/0
@@ -11,6 +13,9 @@
 -define(LIST_STAGED,
         "git diff --name-status --staged | awk '$1 != \"D\" { print $2 }'").
 
+-define(LIST_BRANCH_CHANGES(B),
+        "git diff --name-only --ignore-submodules=all --diff-filter=d " ++ B).
+
 -define(STAGED_CONTENT(Path),
         "git show :" ++ Path).
 
@@ -29,6 +34,25 @@ run_hook(Config) ->
         ok -> ok
     end.
 
+-spec run_branch(string(), elvis_config:config()) -> ok.
+run_branch(Branch, Config) ->
+    Files = elvis_git:branch_files(Branch),
+    Results = lists:map(fun(File) ->
+                                elvis_core:rock_this(File, Config)
+                        end, Files),
+    case lists:any(fun(Res) -> Res /= ok end, Results) of
+        true -> elvis_utils:erlang_halt(1);
+        false -> ok
+    end.
+
+-spec branch_files(string()) -> [elvis_file:file()].
+branch_files(Branch) ->
+    Cmd = ?LIST_BRANCH_CHANGES(Branch),
+    Output = list_to_binary(os:cmd(Cmd)),
+
+    Lines = binary:split(Output, <<"\n">>, [global]),
+    [binary_to_list(Path) || Path <- Lines, byte_size(Path) > 0].
+
 -spec staged_files() -> [elvis_file:file()].
 staged_files() ->
     Cmd = ?LIST_STAGED,

test/git_SUITE.erl

@@ -7,7 +7,8 @@
 -export([
          relative_position_from_patch/1,
          check_staged_files/1,
-         ignore_deleted_files/1
+         ignore_deleted_files/1,
+         check_branch_files/1
         ]).
 
 -define(EXCLUDED_FUNS,
@@ -66,16 +67,17 @@ relative_position_from_patch(_Config) ->
 
 -spec check_staged_files(config()) -> any().
 check_staged_files(_Config) ->
-    Filename = "../../temp_file_test",
-    ok = file:write_file(Filename, <<"sdsds">>, [append]),
+    FileName = random_file_name(),
+    FileLocation = "../../" ++ FileName,
+    ok = file:write_file(FileLocation, <<"sdsds">>, [append]),
 
-    _ = os:cmd("git add " ++ Filename),
+    _ = os:cmd("git add " ++ FileLocation),
     StagedFiles = elvis_git:staged_files(),
-    FilterFun = fun (#{path := Path}) -> Path == "temp_file_test" end,
+    FilterFun = fun (#{path := Path}) -> Path == FileName end,
     [_] = lists:filter(FilterFun, StagedFiles),
-    _ = os:cmd("git reset " ++ Filename),
+    _ = os:cmd("git reset " ++ FileLocation),
 
-    file:delete(Filename).
+    file:delete(FileLocation).
 
 -spec ignore_deleted_files(config()) -> any().
 ignore_deleted_files(Config) ->
@@ -92,3 +94,25 @@ ignore_deleted_files(Config) ->
     StagedFiles = lists:sort([Path
                               || #{path := Path} <- elvis_git:staged_files()]),
     ["test2", "test3"] = StagedFiles.
+
+-spec check_branch_files(config()) -> any().
+check_branch_files(_Config) ->
+    _ = os:cmd("git stash"),
+
+    FileName = random_file_name(),
+    FileLocation = "../../" ++ FileName,
+    ok = file:write_file(FileLocation, <<"sdsds">>, [append]),
+
+    _ = os:cmd("git add " ++ FileLocation),
+    _ = os:cmd("git commit -m \"some commit\""),
+    [FileName] = elvis_git:branch_files("HEAD^"),
+    _ = os:cmd("git reset --hard HEAD^"),
+
+    _ = os:cmd("git stash pop"),
+
+    file:delete(FileLocation).
+
+-spec random_file_name() -> string().
+random_file_name() ->
+  RandomString = integer_to_list(crypto:rand_uniform(0, 1 bsl 127)),
+  "test_file_" ++ RandomString.