tools: Add git diff.

- This is worth it afterall.
- Eris will get out of sync when the diffs are commited,
  but this is also true of git-blame and git-log.
- The user can refresh the old results with shift-r.

README.md

@@ -46,9 +46,9 @@ There is a wrapper script available to make running easier:
 
 ## Tools
 
-File types(100) | Tools(59)
+File types(100) | Tools(60)
 ----------:| -----
-.* | [contents](http://pygments.org/) • [metadata](https://github.com/ahamilton/eris) • [git_blame](https://git-scm.com/docs/git-blame) • [git_log](https://git-scm.com/docs/git-log)
+.* | [contents](http://pygments.org/) • [metadata](https://github.com/ahamilton/eris) • [git_diff](https://git-scm.com/docs/git-diff) • [git_blame](https://git-scm.com/docs/git-blame) • [git_log](https://git-scm.com/docs/git-log)
 .py | [python_syntax](https://en.wikipedia.org/wiki/Python_syntax_and_semantics) • [python_unittests](https://docs.python.org/3/library/unittest.html) • [pytest](https://docs.pytest.org/en/latest/) • [pydoc](https://docs.python.org/3/library/pydoc.html) • [mypy](http://mypy-lang.org/) • [python_coverage](https://coverage.readthedocs.io/) • [pycodestyle](http://pycodestyle.pycqa.org/en/latest/) • [pydocstyle](http://www.pydocstyle.org/en/2.1.1/usage.html) • [pyflakes](https://pypi.org/project/pyflakes/) • [pylint](https://www.pylint.org/) • [python_gut](https://github.com/ahamilton/eris) • [python_modulefinder](https://docs.python.org/3/library/modulefinder.html) • [dis](https://docs.python.org/3/library/dis.html) • [python_mccabe](https://pypi.org/project/mccabe/) • [bandit](https://pypi.org/project/bandit/)
 .pl .pm .t | [perl_syntax](https://en.wikipedia.org/wiki/Perl) • [perldoc](http://perldoc.perl.org/)
 .p6 .pm6 | [perl6_syntax](https://rakudo.org/)

eris/tools.py

@@ -510,7 +510,7 @@ def make_tool_function(dependencies, command, url=None, success_status=None,
     return func
 
 
-elinks, git_blame = None, None  # For linters.
+elinks, git_diff, git_blame = None, None, None  # For linters.
 with importlib.resources.open_text(eris, "tools.toml") as tools_toml_file:
     tools_toml = toml.load(tools_toml_file)
 tools_for_extensions = tools_toml["tools_for_extensions"]
@@ -685,6 +685,7 @@ def _tools_for_extension():
 
 def tools_all():
     tools_ = set(generic_tools())
+    tools_.add(git_diff)
     tools_.add(git_blame)
     tools_.add(git_log)
     for tool_list in _tools_for_extension().values():
@@ -727,7 +728,7 @@ def is_tool_available(tool):
 
 
 def tools_for_path(path):
-    git_tools = [git_blame, git_log] if os.path.exists(".git") else []
+    git_tools = [git_diff, git_blame, git_log] if os.path.exists(".git") else []
     root, ext = splitext(path)
     extra_tools = [] if ext == "" else _tools_for_extension().get(ext[1:], [])
     tools = generic_tools() + git_tools + extra_tools

eris/tools.toml

@@ -111,6 +111,14 @@ tools_for_extensions = [
   error_status = "not_applicable"
   has_color = true
 
+[git_diff]
+  dependencies = ["git"]
+  url = "https://git-scm.com/docs/git-diff"
+  command = "git diff --word-diff=color --exit-code"
+  success_status = "normal"
+  error_status = "problem"
+  has_color = true
+
 [git_blame]
   dependencies = ["git"]
   url = "https://git-scm.com/docs/git-blame"

make-readme.py

@@ -7,7 +7,7 @@ import eris.tools as tools
 
 def main():
     all_tools = ([(["*"], tools.generic_tools() +
-                   [tools.git_blame, tools.git_log])] +
+                   [tools.git_diff, tools.git_blame, tools.git_log])] +
                  tools.TOOLS_FOR_EXTENSIONS)
     tool_set = set()
     extension_set = set()