Renames zipline.utils.test_utils to zipline.testing
Adds zipline.testing.fixtures.ZiplineTestCase to manage setup and
teardown and adds mixins to define fixtures like an asset finder or
trading calendar.
Previously we have capitalized input strings at different levels in
our code: in the user-facing API methods and in the asset finder.
This commit moves input string capitalization exclusively to the API
method to which the string was supplied. Specifically, the string is
capitalized by a preprocess API method decorator. The preprocess
decorator passes the input string to the newly defined
ensure_upper_case() method, which returns a TypeError if the argument
supplied is not a string.
ensure_upper_case() is defined in a new file, zipline/utils/input_validation.py.
The existing expect_types() method is also moved there.
Various tests in tests/test_assets.py are modified to account for the
fact that the asset finder method lookup_symol() no longer capitalizes
its supplied argument.
'instant fill' execution may be on the path to deprecation, (the removal
is currently proposed by the branch which removes events in favor of
operating over dts.), so remove instant_fill from the close position
tests so that the input and output is the same between the proposed
branch and here.
(This was one of the few places where instant fill was used that
was not testing instant fill behavior explicitly, so may be better to
align this test with the rest of the suite.)
Also, change test methods to make it more clear on which day the values
the expected and actual results differed.
lookup_symbol_resolve_multiple was identical to lookup_symbol, except that lookup_symbol performed upper-casing of the input string and lookup_symbol would return Nones. Now, lookup_symbol has a kwarg 'default_None=True' and all symbols are upper-cased on insertion and request.
This commit removes the ability to reference a shared TradingEnvironment through the zipline.finance.trading module. In place, the classes that require a TradingEnvironment, or its child AssetFinder, contain their own references to those objects.
This commit also adds serialization utilities that allow for the pickling/unpickling of objects without unintentionally their TradingEnvironments or AssetFinders.
This patch lays the groundwork for a compute engine designed to
facilitate construction of factor-based universe screening and portfolio
allocation. It contains:
A new module, `zipline.modelling`, containing entities that can be used
to express computations as dependency graphs. Each node in such a graph
is an instance of the base `Term` class, defined in
`zipline.modelling.term`. Dependency graphs are executed by instances
of `FFCEngine`, defined in `zipline.modelling.engine`.
A new module, `zipline.data.ffc`, containing loaders and dataset
definitions for inputs to the modelling API.
New `TradingAlgorithm` api methods: `add_factor`, and `add_filter`.
These methods can only be called from `initialize`, and are used to
inform the algorithm that each day it should compute the given terms.
Computed factor results are made available through a new attribute of
the `data` object in `before_trading_start` and `handle_data`. Computed
filter results control which assets are available in the factor matrix
on each day.
Attack the startup bottleneck of creating the asset finders caches for a
large universe, which was between 1-2 seconds on development and
production machines.
Instead, allow the AssetFinder to be passed a sqlite3 file that has
already been populated and then hydrate asset objects only when an
equity is referenced for the first time.
To create aforementioned sqlite3, create an AssetFinder with an db_path
and `create_table` set to True. If `create_table` is set to False, the
prepopulated data in the sqlite file found at db_path will be used.
Default behavior is to use an in memory database.
Behavior that changes:
- Fuzzy lookup now only works on one character, that character needs to be
specified at write/metadata consumption time, since the fuzzy lookup key
is created by dropping the character from each symbol.
- Overwriting partially written metadata is no longer
supported. i.e. some unit tests allowed for inserting just the identifier,
and then later updating the symbol, end_date, etc.
Instead of building an upsert behavior at this time, this patch
changes the unit tests so that the data for each asset is only
inserted once.
Other notes:
- populate_cache is now removed, since there is no longer a two step
process of inserting metadata and then realizing that metadata into
assets. _spawn_asset is rolled into insert_metadata, so that a call to
insert_metadata both converts the metadata and makes it available in
the data store.
The lookup of future contract by individual symbol is a constraint on
incoming changes of changing how the asset finder stores data.
(i.e. the asset finder is changing so that there are separate tables for
both futures and equities.)
Since this lookup is not yet fully supported, we can add it back in on
top of the new asset finder.
Test sources are now defined by the sim_params period_start and period_end, rather than by the period_start and a defined 'count' of bars. This allows us to consider the sim_params.period_end as the canonical definition of the end of a simulation.
Joe Jevnik