hooks.ledger_entry: New hook to output Ledger entries.

This is roughly the smallest diff necessary to move output to a hook.
There's a lot of code reorganization that should still happen to bring it
better in line with this new structure.

import2ledger/__main__.py

@@ -22,17 +22,7 @@ class FileImporter:
         for importer in self.importers:
             in_file.seek(0)
             if importer.can_import(in_file):
-                try:
-                    template = self.config.get_template(importer.TEMPLATE_KEY)
-                except errors.UserInputConfigurationError as error:
-                    if error.strerror.startswith('template not defined '):
-                        have_template = False
-                    else:
-                        raise
-                else:
-                    have_template = not template.is_empty()
-                if have_template:
-                    importers.append((importer, template))
+                importers.append(importer)
         if not importers:
             raise errors.UserInputFileError("no importers available", in_file.name)
         source_vars = {
@@ -43,21 +33,19 @@ class FileImporter:
             'source_path': in_path.as_posix(),
             'source_stem': in_path.stem,
         }
-        with self.config.open_output_file() as out_file:
-            for importer, template in importers:
-                in_file.seek(0)
-                for entry_data in importer(in_file):
-                    for hook in self.hooks:
-                        hook_retval = hook.run(entry_data)
-                        if hook_retval is None:
-                            pass
-                        elif hook_retval is False:
-                            break
-                        else:
-                            entry_data = hook_retval
+        for importer in importers:
+            in_file.seek(0)
+            source_vars['template'] = importer.TEMPLATE_KEY
+            for entry_data in importer(in_file):
+                entry_data = collections.ChainMap(entry_data, source_vars)
+                for hook in self.hooks:
+                    hook_retval = hook.run(entry_data)
+                    if hook_retval is None:
+                        pass
+                    elif hook_retval is False:
+                        break
                     else:
-                        render_vars = collections.ChainMap(entry_data, source_vars)
-                        print(template.render(render_vars), file=out_file, end='')
+                        entry_data = hook_retval
 
     def import_path(self, in_path):
         if in_path is None:

import2ledger/hooks/__init__.py

@@ -19,6 +19,8 @@ HOOK_KINDS = enum.Enum('HOOK_KINDS', [
     # DATA_FILTER hooks make a decision about whether or not to proceed with
     # processing the entry.
     'DATA_FILTER',
+    # OUTPUT hooks run last, sending the data somewhere else.
+    'OUTPUT',
 ])
 
 def load_all():

import2ledger/hooks/ledger_entry.py

@@ -0,0 +1,23 @@
+from . import HOOK_KINDS
+
+from .. import errors
+
+class LedgerEntryHook:
+    KIND = HOOK_KINDS.OUTPUT
+
+    def __init__(self, config):
+        self.config = config
+
+    def run(self, entry_data):
+        try:
+            template = self.config.get_template(entry_data['template'])
+        except errors.UserInputConfigurationError as error:
+            if error.strerror.startswith('template not defined '):
+                have_template = False
+            else:
+                raise
+        else:
+            have_template = not template.is_empty()
+        if have_template:
+            with self.config.open_output_file() as out_file:
+                print(template.render(entry_data), file=out_file, end='')

tests/data/templates.ini

@@ -40,3 +40,8 @@ template =
  ; :NonItem:
  Income:Sales  -{item_sales}
  ; :Item:
+
+[Empty]
+template =
+
+[Nonexistent]

tests/test_hooks.py

@@ -5,13 +5,19 @@ import itertools
 import pytest
 
 from import2ledger import hooks
-from import2ledger.hooks import add_entity, default_date, filter_by_date
+from import2ledger.hooks import add_entity, default_date, filter_by_date, ledger_entry
 
 def test_load_all():
     all_hooks = list(hooks.load_all())
     positions = {hook: index for index, hook in enumerate(all_hooks)}
-    assert positions[default_date.DefaultDateHook] < positions[add_entity.AddEntityHook]
-    assert positions[add_entity.AddEntityHook] < positions[filter_by_date.FilterByDateHook]
+    expected_order = [
+        default_date.DefaultDateHook,
+        add_entity.AddEntityHook,
+        filter_by_date.FilterByDateHook,
+        ledger_entry.LedgerEntryHook,
+    ]
+    actual_order = list(sorted(expected_order, key=positions.__getitem__))
+    assert actual_order == expected_order
 
 @pytest.mark.parametrize('in_key,payee,out_key,expected', [
     ('payee', 'Alex Smith', 'entity', 'Smith-Alex'),

tests/test_templates.py

@@ -1,11 +1,14 @@
 import collections
 import configparser
+import contextlib
 import datetime
 import decimal
+import io
 import pathlib
 
 import pytest
 from import2ledger import errors, template
+from import2ledger.hooks import ledger_entry
 
 from . import DATA_DIR, normalize_whitespace
 
@@ -199,3 +202,48 @@ def test_line1_not_custom_payee():
 def test_bad_amount_expression(amount_expr):
     with pytest.raises(errors.UserInputError):
         template.Template(" Income  " + amount_expr)
+
+class Config:
+    def __init__(self):
+        self.stdout = io.StringIO()
+
+    @contextlib.contextmanager
+    def open_output_file(self):
+        yield self.stdout
+
+    def get_template(self, key):
+        try:
+            return template_from(key)
+        except KeyError:
+            raise errors.UserInputConfigurationError(
+                "template not defined in test config", key)
+
+
+def run_hook(entry_data):
+    hook_config = Config()
+    hook = ledger_entry.LedgerEntryHook(hook_config)
+    assert hook.run(entry_data) is None
+    stdout = hook_config.stdout.getvalue()
+    return normalize_whitespace(stdout).splitlines()
+
+def hook_vars(template_key, payee, amount):
+    return template_vars(payee, amount, other_vars={'template': template_key})
+
+def test_hook_renders_template():
+    entry_data = hook_vars('Simplest', 'BB', '0.99')
+    lines = run_hook(entry_data)
+    assert lines == [
+        "",
+        "2015/03/14 BB",
+        "  Accrued:Accounts Receivable  0.99 USD",
+        "  Income:Donations  -0.99 USD",
+    ]
+
+def test_hook_handles_empty_template():
+    entry_data = hook_vars('Empty', 'CC', 1)
+    assert not run_hook(entry_data)
+
+def test_hook_handles_template_undefined():
+    entry_data = hook_vars('Nonexistent', 'DD', 1)
+    assert not run_hook(entry_data)
+