add specific-schema feature, format, version bump, readme update

Makefile

@@ -29,9 +29,11 @@ docs:
 docsserve:
 	cd docs && mkdocs serve
 
+fmt:
+	black .
+
 lint:
-	flake8 migra
-	flake8 tests
+	flake8 .
 
 tidy: clean lint
 

README.md

@@ -1,5 +1,20 @@
 # migra: PostgreSQL migrations made almost painless
 
+`migra` is a schema diff tool for PostgreSQL. Use it to compare database schemas or autogenerate migration scripts. Use it in your python scripts, or from the command line like this:
+
+    $ migra postgresql:///a postgresql:///b
+    alter table "public"."products" add column newcolumn text;
+
+    alter table "public"."products" add constraint "x" CHECK ((price > (0)::numeric));
+
+`migra` magically figures out all the statements required to get from A to B.
+
+You can also detect changes for a single specific schema only with `--schema myschema`.
+
+## Already use `migra`? [Let us know how you're using it and what features would make it more useful](https://github.com/djrobstep/migra/issues/25).
+
+## Folks, schemas are good
+
 Schema migrations are without doubt the most cumbersome and annoying part of working with SQL databases. So much so that some people think that schemas themselves are bad!
 
 But schemas are actually good. Enforcing data consistency and structure is a good thing. It’s the migration tooling that is bad, because it’s harder to use than it should be. ``migra`` is an attempt to change that, and make migrations easy, safe, and reliable instead of something to dread.
@@ -8,7 +23,7 @@ But schemas are actually good. Enforcing data consistency and structure is a goo
 
 ## Full documentation
 
-Official documentation is at [migra.djrobstep.com](https://migra.djrobstep.com).
+Documentation is at [migra.djrobstep.com](https://migra.djrobstep.com).
 
 ## How it Works
 
@@ -16,18 +31,21 @@ Think of `migra` as a diff tool for schemas. Suppose database A and database B h
 
 This includes changes to tables, views, functions, indexes, constraints, enums, sequences, and installed extensions.
 
-You can use `migra` as a library to build your own migration scripts, tools, etc. Installing migra also installs the `migra` command, so you can use it as follows:
+You can also use `migra` as a library to build your own migration scripts, tools, and custom migration flows.
 
-    $ migra postgresql:///a postgresql:///b
-    alter table "public"."products" add column newcolumn text;
+With migra, a typical database migration is a simple three step process.
 
-    alter table "public"."products" add constraint "x" CHECK ((price > (0)::numeric));
+1. Autogenerate:
 
-If *b* is the target schema, then a new column and constraint needs to be applied to *a* to make it match *b*'s schema. Once we've reviewed the autogenerated SQL and we're happy with it, we can apply these changes as easily as:
+        $ migra --unsafe postgresql:///a postgresql:///b > migration_script.sql
 
-    $ migra --unsafe postgresql:///a postgresql:///b > migration_script.sql
-    # Then after careful review (obviously)...
-    $ psql a --single-transaction -f migration_script.sql
+2. Review (and tweak if necessary).
+
+        # If you need to move data about during your script, you can add those changes to your script.
+
+3. Apply:
+
+        $ psql a --single-transaction -f migration_script.sql
 
 Migration complete!
 
@@ -35,6 +53,8 @@ Migration complete!
 
 **Migrations can never be fully automatic**. As noted above **ALWAYS REVIEW MIGRATION SCRIPTS CAREFULLY, ESPECIALLY WHEN DROPPING TABLES IS INVOLVED**.
 
+Migra manages schema changes **but not your data**. If you need to move data around, as part of a migration, you'll need to handle that by editing the script or doing it separately before/after the schema changes.
+
 Best practice is to run your migrations against a copy of your production database first. This helps verify correctness and spot any performance issues before they cause interruptions and downtime on your production database.
 
 `migra` will deliberately throw an error if any generated statements feature the word "drop". This safety feature is by no means idiot-proof, but might prevent a few obvious blunders.
@@ -61,8 +81,7 @@ As you can see, it's pretty simple (`S` here is a context manager that creates a
 
 Here the code just opens connections to both databases for the Migration object to analyse. `m.add_all_changes()` generates the SQL statements for the changes required, and adds to the migration object's list of pending changes. The necessary SQL is now available as a property.
 
-Features and Limitations
-------------------------
+## Features and Limitations
 
 `migra` plays nicely with extensions. Schema contents belonging to extensions will be ignored and left to the extension to manage.
 
@@ -70,13 +89,16 @@ Features and Limitations
 
 Only SQL/PLPGSQL functions are confirmed to work so far. `migra` ignores functions that use other languages.
 
-Installation
-------------
+## Installation
 
-Assuming you have `pip <https://pip.pypa.io>`_ installed, all you need to do is install as follows:
+Assuming you have [pip](https://pip.pypa.io), all you need to do is install as follows:
 
     $ pip install migra
 
-If you don't have psycopg2 (the PostgreSQL driver) installed yet, you can install this at the same time with:
+If you don't have psycopg2-binary (the PostgreSQL driver) installed yet, you can install this at the same time with:
 
     $ pip install migra[pg]
+
+## Contributing
+
+Contributing is easy. [Jump into the issues](https://github.com/djrobstep/migra/issues), find a feature or fix you'd like to work on, and get involved. Or create a new issue and suggest something completely different. Beginner-friendly issues are tagged "good first issue", and if you're unsure about any aspect of the process, just ask.

migra/__init__.py

@@ -6,8 +6,5 @@ from .migra import Migration
 from .command import do_command
 
 __all__ = [
-    'Migration',
-    'Changes',
-    'Statements',
-    'UnsafeMigrationException',
-    'do_command']
+    'Migration', 'Changes', 'Statements', 'UnsafeMigrationException', 'do_command'
+]

migra/changes.py

@@ -13,44 +13,36 @@ THINGS = [
     'functions',
     'views',
     'indexes',
-    'extensions'
+    'extensions',
 ]
-
 PK = 'PRIMARY KEY'
 
 
 def statements_for_changes(
-        things_from,
-        things_target,
-        creations_only=False,
-        drops_only=False,
-        modifications=True,
-        dependency_ordering=False,
-        add_dependents_for_modified=False):
-
-    added, removed, modified, unmodified = \
-        differences(things_from, things_target)
-
+    things_from,
+    things_target,
+    creations_only=False,
+    drops_only=False,
+    modifications=True,
+    dependency_ordering=False,
+    add_dependents_for_modified=False,
+):
+    added, removed, modified, unmodified = differences(things_from, things_target)
     if add_dependents_for_modified:
         for k, m in list(modified.items()):
             for d in m.dependents_all:
                 if d in unmodified:
                     modified[d] = unmodified.pop(d)
         modified = od(sorted(modified.items()))
-
     statements = Statements()
-
     if not creations_only:
         pending_drops = set(removed)
-
         if modifications:
             pending_drops |= set(modified)
     else:
         pending_drops = set()
-
     if not drops_only:
         pending_creations = set(added)
-
         if modifications:
             pending_creations |= set(modified)
     else:
@@ -59,30 +51,29 @@ def statements_for_changes(
     def has_remaining_dependents(v, pending_drops):
         if not dependency_ordering:
             return False
+
         return bool(set(v.dependents) & pending_drops)
 
     def has_uncreated_dependencies(v, pending_creations):
         if not dependency_ordering:
             return False
+
         return bool(set(v.dependent_on) & pending_creations)
 
     while True:
         before = pending_drops | pending_creations
-
         if not creations_only:
             for k, v in removed.items():
                 if not has_remaining_dependents(v, pending_drops):
                     if k in pending_drops:
                         statements.append(v.drop_statement)
                         pending_drops.remove(k)
-
         if not drops_only:
             for k, v in added.items():
                 if not has_uncreated_dependencies(v, pending_creations):
                     if k in pending_creations:
                         statements.append(v.create_statement)
                         pending_creations.remove(k)
-
         if modifications:
             for k, v in modified.items():
                 if not creations_only:
@@ -90,15 +81,12 @@ def statements_for_changes(
                         if k in pending_drops:
                             statements.append(v.drop_statement)
                             pending_drops.remove(k)
-
                 if not drops_only:
                     if not has_uncreated_dependencies(v, pending_creations):
                         if k in pending_creations:
                             statements.append(v.create_statement)
                             pending_creations.remove(k)
-
         after = pending_drops | pending_creations
-
         if not after:
             break
 
@@ -108,78 +96,53 @@ def statements_for_changes(
     return statements
 
 
-def get_enum_modifications(
-        tables_from,
-        tables_target,
-        enums_from,
-        enums_target):
-
+def get_enum_modifications(tables_from, tables_target, enums_from, enums_target):
     _, _, e_modified, _ = differences(enums_from, enums_target)
     _, _, t_modified, _ = differences(tables_from, tables_target)
-
     pre = Statements()
     recreate = Statements()
     post = Statements()
-
     enums_to_change = e_modified
-
     for t, v in t_modified.items():
         t_before = tables_from[t]
-
         _, _, c_modified, _ = differences(t_before.columns, v.columns)
-
         for k, c in c_modified.items():
             before = t_before.columns[k]
-
             if c.is_enum == before.is_enum and c.dbtypestr == before.dbtypestr and c.enum != before.enum:
                 pre.append(before.change_enum_to_string_statement(t))
                 post.append(before.change_string_to_enum_statement(t))
-
     for e in enums_to_change.values():
         recreate.append(e.drop_statement)
         recreate.append(e.create_statement)
-
     return pre + recreate + post
 
 
-def get_schema_changes(
-        tables_from,
-        tables_target,
-        enums_from,
-        enums_target):
-
+def get_schema_changes(tables_from, tables_target, enums_from, enums_target):
     added, removed, modified, _ = differences(tables_from, tables_target)
-
     statements = Statements()
-
     for t, v in removed.items():
         statements.append(v.drop_statement)
-
     for t, v in added.items():
         statements.append(v.create_statement)
-
-    statements += get_enum_modifications(tables_from, tables_target, enums_from, enums_target)
-
+    statements += get_enum_modifications(
+        tables_from, tables_target, enums_from, enums_target
+    )
     for t, v in modified.items():
         before = tables_from[t]
-        c_added, c_removed, c_modified, _ = \
-            differences(before.columns, v.columns)
-
+        c_added, c_removed, c_modified, _ = differences(before.columns, v.columns)
         for k, c in c_removed.items():
             alter = v.alter_table_statement(c.drop_column_clause)
             statements.append(alter)
-
         for k, c in c_added.items():
             alter = v.alter_table_statement(c.add_column_clause)
             statements.append(alter)
-
         for k, c in c_modified.items():
             statements += c.alter_table_statements(before.columns[k], t)
-
     return statements
 
 
 class Changes(object):
+
     def __init__(self, i_from, i_target):
         self.i_from = i_from
         self.i_target = i_target
@@ -191,45 +154,42 @@ class Changes(object):
                 self.i_from.tables,
                 self.i_target.tables,
                 self.i_from.enums,
-                self.i_target.enums)
+                self.i_target.enums,
+            )
+
         elif name == 'non_pk_constraints':
             a = self.i_from.constraints.items()
             b = self.i_target.constraints.items()
-
             a_od = od((k, v) for k, v in a if v.constraint_type != PK)
             b_od = od((k, v) for k, v in b if v.constraint_type != PK)
-
             return partial(statements_for_changes, a_od, b_od)
+
         elif name == 'pk_constraints':
             a = self.i_from.constraints.items()
             b = self.i_target.constraints.items()
-
             a_od = od((k, v) for k, v in a if v.constraint_type == PK)
             b_od = od((k, v) for k, v in b if v.constraint_type == PK)
-
             return partial(statements_for_changes, a_od, b_od)
+
         elif name == 'views_and_functions':
             av = self.i_from.views.items()
             bv = self.i_target.views.items()
-
             af = self.i_from.functions.items()
             bf = self.i_target.functions.items()
-
             avf = list(av) + list(af)
             bvf = list(bv) + list(bf)
-
             avf = od(sorted(avf))
             bvf = od(sorted(bvf))
-
             return partial(
-                statements_for_changes,
-                avf,
-                bvf,
-                add_dependents_for_modified=True)
+                statements_for_changes, avf, bvf, add_dependents_for_modified=True
+            )
+
         elif name in THINGS:
             return partial(
                 statements_for_changes,
                 getattr(self.i_from, name),
-                getattr(self.i_target, name))
+                getattr(self.i_target, name),
+            )
+
         else:
             raise AttributeError(name)

migra/command.py

@@ -13,57 +13,67 @@ from .statements import UnsafeMigrationException
 def arg_context(x):
     if x == 'EMPTY':
         yield None
+
     else:
         with S(x) as s:
             yield s
 
 
 def parse_args(args):
-    parser = argparse.ArgumentParser(
-        description='Generate a database migration.')
-
+    parser = argparse.ArgumentParser(description='Generate a database migration.')
     parser.add_argument(
         '--unsafe',
         dest='unsafe',
         action='store_true',
-        help='Prevent migra from erroring upon generation of drop statements.')
-
+        help='Prevent migra from erroring upon generation of drop statements.',
+    )
     parser.add_argument(
-        'dburl_from',
-        help='The database you want to migrate.')
-
+        '--schema',
+        dest='schema',
+        default=None,
+        help='Restrict output to statements for a particular schema',
+    ),
     parser.add_argument(
-        'dburl_target',
-        help='The database you want to use as the target.')
-
+        '--create-extensions-only',
+        dest='create_extensions_only',
+        action='store_true',
+        default=False,
+        help='Only output "create extension..." statements, nothing else.',
+    ),
+    parser.add_argument('dburl_from', help='The database you want to migrate.')
+    parser.add_argument(
+        'dburl_target', help='The database you want to use as the target.'
+    )
     return parser.parse_args(args)
 
 
 def run(args, out=None, err=None):
+    schema = args.schema
     if not out:
         out = sys.stdout  # pragma: no cover
-
     if not err:
         err = sys.stderr  # pragma: no cover
-
-    with \
-            arg_context(args.dburl_from) as ac0, \
-            arg_context(args.dburl_target) as ac1:
-        m = Migration(ac0, ac1)
-
+    with arg_context(args.dburl_from) as ac0, arg_context(args.dburl_target) as ac1:
+        m = Migration(ac0, ac1, schema=schema)
         if args.unsafe:
             m.set_safety(False)
-        m.add_all_changes()
-
+        if args.create_extensions_only:
+            m.add_extension_changes(drops=False)
+        else:
+            m.add_all_changes()
         try:
             if m.statements:
                 print(m.sql, file=out)
         except UnsafeMigrationException:
-            print('-- ERROR: destructive statements generated. Use the --unsafe flag to suppress this error.', file=err)
+            print(
+                '-- ERROR: destructive statements generated. Use the --unsafe flag to suppress this error.',
+                file=err,
+            )
             return 3
 
         if not m.statements:
             return 0
+
         else:
             return 2
 

migra/migra.py

@@ -10,29 +10,29 @@ class Migration(object):
     """
     The main class of migra
     """
-    def __init__(self, x_from, x_target):
+
+    def __init__(self, x_from, x_target, schema=None):
         self.statements = Statements()
         self.changes = Changes(None, None)
-
+        self.schema = schema
         if isinstance(x_from, DBInspector):
             self.changes.i_from = x_from
         else:
-            self.changes.i_from = get_inspector(x_from)
+            self.changes.i_from = get_inspector(x_from, schema=schema)
             if x_from:
                 self.s_from = x_from
-
         if isinstance(x_target, DBInspector):
             self.changes.i_target = x_target
         else:
-            self.changes.i_target = get_inspector(x_target)
+            self.changes.i_target = get_inspector(x_target, schema=schema)
             if x_target:
                 self.s_target = x_target
 
     def inspect_from(self):
-        self.changes.i_from = get_inspector(self.s_from)
+        self.changes.i_from = get_inspector(self.s_from, schema=self.schema)
 
     def inspect_target(self):
-        self.changes.i_target = get_inspector(self.s_target)
+        self.changes.i_target = get_inspector(self.s_target, schema=self.schema)
 
     def clear(self):
         self.statements = Statements()
@@ -40,8 +40,7 @@ class Migration(object):
     def apply(self):
         for stmt in self.statements:
             raw_execute(self.s_from, stmt)
-
-        self.changes.i_from = get_inspector(self.s_from)
+        self.changes.i_from = get_inspector(self.s_from, schema=self.schema)
         safety_on = self.statements.safe
         self.clear()
         self.set_safety(safety_on)
@@ -55,37 +54,36 @@ class Migration(object):
     def set_safety(self, safety_on):
         self.statements.safe = safety_on
 
+    def add_extension_changes(self, creates=True, drops=True):
+        if creates:
+            self.add(self.changes.extensions(creations_only=True))
+        if drops:
+            self.add(self.changes.extensions(drops_only=True))
+
     def add_all_changes(self):
         self.add(self.changes.schemas(creations_only=True))
-
         self.add(self.changes.extensions(creations_only=True))
         self.add(self.changes.enums(creations_only=True, modifications=False))
         self.add(self.changes.sequences(creations_only=True))
-
         self.add(self.changes.non_pk_constraints(drops_only=True))
         self.add(self.changes.pk_constraints(drops_only=True))
         self.add(self.changes.indexes(drops_only=True))
-
-        self.add(self.changes.views_and_functions(drops_only=True, dependency_ordering=True))
-
+        self.add(
+            self.changes.views_and_functions(drops_only=True, dependency_ordering=True)
+        )
         self.add(self.changes.schema())
-
-        v_and_f_changes = self.changes.views_and_functions(creations_only=True, dependency_ordering=True)
-
+        v_and_f_changes = self.changes.views_and_functions(
+            creations_only=True, dependency_ordering=True
+        )
         if v_and_f_changes:
-            self.add([
-                'set check_function_bodies = off;'
-            ])
+            self.add(['set check_function_bodies = off;'])
             self.add(v_and_f_changes)
-
         self.add(self.changes.sequences(drops_only=True))
         self.add(self.changes.enums(drops_only=True, modifications=False))
         self.add(self.changes.extensions(drops_only=True))
-
         self.add(self.changes.indexes(creations_only=True))
         self.add(self.changes.pk_constraints(creations_only=True))
         self.add(self.changes.non_pk_constraints(creations_only=True))
-
         self.add(self.changes.schemas(drops_only=True))
 
     @property

migra/statements.py

@@ -8,6 +8,7 @@ def check_for_drop(s):
 
 
 class Statements(list):
+
     def __init__(self, *args, **kwargs):
         self.safe = True
         super(Statements, self).__init__(*args, **kwargs)
@@ -18,11 +19,14 @@ class Statements(list):
             self.raise_if_unsafe()
         if not self:
             return ''
+
         return '\n\n'.join(self) + '\n\n'
 
     def raise_if_unsafe(self):
         if any(check_for_drop(s) for s in self):
-            raise UnsafeMigrationException('unsafe/destructive change being autogenerated, refusing to carry on further')
+            raise UnsafeMigrationException(
+                'unsafe/destructive change being autogenerated, refusing to carry on further'
+            )
 
     def __add__(self, other):
         self += list(other)

migra/util.py

@@ -4,17 +4,13 @@ from collections import OrderedDict as od
 
 
 def differences(a, b, add_dependencies_for_modifications=True):
-
     a_keys = set(a.keys())
     b_keys = set(b.keys())
-
     keys_added = set(b_keys) - set(a_keys)
     keys_removed = set(a_keys) - set(b_keys)
     keys_common = set(a_keys) & set(b_keys)
-
     added = od((k, b[k]) for k in sorted(keys_added))
     removed = od((k, a[k]) for k in sorted(keys_removed))
     modified = od((k, b[k]) for k in sorted(keys_common) if a[k] != b[k])
     unmodified = od((k, b[k]) for k in sorted(keys_common) if a[k] == b[k])
-
     return added, removed, modified, unmodified

requirements.txt

@@ -11,7 +11,7 @@ pylint
 autopep8
 flake8
 
-psycopg2
+psycopg2-binary
 
 tox
 yapf
@@ -22,3 +22,4 @@ twine
 
 mkdocs
 doc2md
+black

setup.py

@@ -1,25 +1,19 @@
 #!/usr/bin/env python
-
 import io
 
 from setuptools import setup, find_packages
 
 readme = io.open('README.md').read()
-
 setup(
     name='migra',
-    version='1.0.1519192543',
+    version='1.0.1521442627',
     url='https://github.com/djrobstep/migra',
     description='Like diff but for PostgreSQL schemas',
     long_description=readme,
     long_description_content_type='text/markdown',
     author='Robert Lechte',
     author_email='robertlechte@gmail.com',
-    install_requires=[
-        'sqlbag',
-        'six',
-        'schemainspect'
-    ],
+    install_requires=['sqlbag', 'six', 'schemainspect'],
     zip_safe=False,
     packages=find_packages(),
     classifiers=[
@@ -32,10 +26,6 @@ setup(
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: Implementation :: CPython',
     ],
-    entry_points={
-        'console_scripts': [
-            'migra = migra:do_command',
-        ],
-    },
-    extras_require={'pg': ['psycopg2-binary']}
+    entry_points={'console_scripts': ['migra = migra:do_command']},
+    extras_require={'pg': ['psycopg2-binary']},
 )

tests/FIXTURES/everything/expected.sql

@@ -1,8 +1,8 @@
 create schema if not exists "evenbetterschema";
 
-create extension "citext" with schema "public" version '1.4';
+create extension if not exists "citext" with schema "public" version '1.4';
 
-create extension "hstore" with schema "public" version '1.4';
+create extension if not exists "hstore" with schema "public" version '1.4';
 
 create type "public"."bug_status" as enum ('new', 'open', 'closed');
 

tests/FIXTURES/everything/expected2.sql

@@ -1,8 +1,8 @@
 create schema if not exists "evenbetterschema";
 
-create extension "citext" with schema "public" version '1.4';
+create extension if not exists "citext" with schema "public" version '1.4';
 
-create extension "hstore" with schema "public" version '1.4';
+create extension if not exists "hstore" with schema "public" version '1.4';
 
 create type "public"."bug_status" as enum ('new', 'open', 'closed');
 

tests/FIXTURES/singleschema/a.sql

@@ -0,0 +1,13 @@
+create extension hstore;
+
+create schema goodschema;
+
+create table goodschema.t(id uuid, value text);
+
+create table t(id uuid, value text);
+
+CREATE TYPE goodschema.sdfasdfasdf AS ENUM ('not shipped', 'shipped', 'delivered');
+
+create index on goodschema.t(id);
+
+create view goodschema.v as select 1;

tests/FIXTURES/singleschema/b.sql

@@ -0,0 +1,9 @@
+create extension citext;
+
+create schema goodschema;
+    
+CREATE TYPE goodschema.sdfasdfasdf AS ENUM ('not shipped', 'shipped', 'delivered', 'not delivered');
+
+create table goodschema.t(id uuid, name text, value text);
+
+create view goodschema.v as select 2;

tests/FIXTURES/singleschema/expected.sql

@@ -0,0 +1,13 @@
+drop index if exists "goodschema"."t_id_idx";
+
+drop view if exists "goodschema"."v" cascade;
+
+drop type "goodschema"."sdfasdfasdf";
+
+create type "goodschema"."sdfasdfasdf" as enum ('not shipped', 'shipped', 'delivered', 'not delivered');
+
+alter table "goodschema"."t" add column "name" text;
+
+set check_function_bodies = off;
+
+create view "goodschema"."v" as  SELECT 2;

tests/FIXTURES/singleschema_ext/a.sql

@@ -0,0 +1,13 @@
+create extension hstore;
+
+create schema goodschema;
+
+create table goodschema.t(id uuid, value text);
+
+create table t(id uuid, value text);
+
+CREATE TYPE goodschema.sdfasdfasdf AS ENUM ('not shipped', 'shipped', 'delivered');
+
+create index on goodschema.t(id);
+
+create view goodschema.v as select 1;

tests/FIXTURES/singleschema_ext/b.sql

@@ -0,0 +1,9 @@
+create extension citext;
+
+create schema goodschema;
+
+CREATE TYPE goodschema.sdfasdfasdf AS ENUM ('not shipped', 'shipped', 'delivered', 'not delivered');
+
+create table goodschema.t(id uuid, name text, value text);
+
+create view goodschema.v as select 2;

tests/FIXTURES/singleschema_ext/expected.sql

@@ -0,0 +1 @@
+create extension if not exists "citext" with schema "public" version '1.4';

tests/test_migra.py

@@ -15,7 +15,6 @@ SQL = """select 1;
 select 2;
 
 """
-
 DROP = 'drop table x;'
 
 
@@ -24,12 +23,9 @@ def test_statements():
     s2 = Statements(['select 2;'])
     s3 = s1 + s2
     assert type(s1) == type(s2) == type(s3)
-
     s3 = s3 + Statements([DROP])
-
     with raises(UnsafeMigrationException):
         assert s3.sql == SQL
-
     s3.safe = False
     SQL_WITH_DROP = SQL + DROP + '\n\n'
     assert s3.sql == SQL_WITH_DROP
@@ -42,81 +38,70 @@ def outs():
 def test_with_fixtures():
     for FIXTURE_NAME in ['dependencies', 'everything']:
         do_fixture_test(FIXTURE_NAME)
+    for FIXTURE_NAME in ['singleschema']:
+        do_fixture_test(FIXTURE_NAME, schema='goodschema')
+    for FIXTURE_NAME in ['singleschema_ext']:
+        do_fixture_test(FIXTURE_NAME, create_extensions_only=True)
 
 
-def do_fixture_test(fixture_name):
+def do_fixture_test(fixture_name, schema=None, create_extensions_only=False):
+    flags = ['--unsafe']
+    if schema:
+        flags += ['--schema', schema]
+    if create_extensions_only:
+        flags += ['--create-extensions-only']
     fixture_path = 'tests/FIXTURES/{}/'.format(fixture_name)
     EXPECTED = io.open(fixture_path + 'expected.sql').read().strip()
-
     with temporary_database() as d0, temporary_database() as d1:
         with S(d0) as s0, S(d1) as s1:
             load_sql_from_file(s0, fixture_path + 'a.sql')
             load_sql_from_file(s1, fixture_path + 'b.sql')
-
         args = parse_args([d0, d1])
         assert not args.unsafe
-
+        assert args.schema is None
         out, err = outs()
         assert run(args, out=out, err=err) == 3
-
         assert out.getvalue() == ''
         assert err.getvalue() == '-- ERROR: destructive statements generated. Use the --unsafe flag to suppress this error.\n'
-
-        args = parse_args(['--unsafe', d0, d1])
+        args = parse_args(flags + [d0, d1])
         assert args.unsafe
-
+        assert args.schema == schema
         out, err = outs()
         assert run(args, out=out, err=err) == 2
         assert err.getvalue() == ''
         assert out.getvalue().strip() == EXPECTED
-
         ADDITIONS = io.open(fixture_path + 'additions.sql').read().strip()
         EXPECTED2 = io.open(fixture_path + 'expected2.sql').read().strip()
-
         if ADDITIONS:
             with S(d0) as s0, S(d1) as s1:
                 m = Migration(s0, s1)
                 m.inspect_from()
                 m.inspect_target()
-
                 with raises(AttributeError):
                     m.changes.nonexist
-
                 m.set_safety(False)
-
                 m.add_sql(ADDITIONS)
                 m.apply()
                 m.add_all_changes()
                 assert m.sql.strip() == EXPECTED2  # sql generated OK
                 m.apply()
-
                 # check for changes again and make sure none are pending
                 m.add_all_changes()
                 assert m.changes.i_from == m.changes.i_target
                 assert not m.statements  # no further statements to apply
                 assert m.sql == ''
-
                 out, err = outs()
                 assert run(args, out=out, err=err) == 0
-
         # test alternative parameters
-
         with S(d0) as s0, S(d1) as s1:
-            m = Migration(
-                get_inspector(s0),
-                get_inspector(s1)
-            )
-
+            m = Migration(get_inspector(s0), get_inspector(s1))
         # test empty
         m = Migration(None, None)
         m.add_all_changes()
-
         with raises(AttributeError):
             m.s_from
-
         with raises(AttributeError):
             m.s_target
-
-        args = parse_args(['--unsafe', 'EMPTY', 'EMPTY'])
+        args = parse_args(flags + ['EMPTY', 'EMPTY'])
         out, err = outs()
         assert run(args, out=out, err=err) == 0