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String localization tests

Project description


localizationkit is a toolkit for ensuring that your localized strings are the best that they can be.

Included are tests for various things such as:

  • Checking that all strings have comments
  • Checking that the comments don't just match the value
  • Check that tokens have position specifiers
  • Check that no invalid tokens are included

with lots more to come.

Getting started


To use the library, first off, create a configuration file that is in the TOML format. Here's an example:

default_language = "en"

minimum_comment_length = 25
minimum_comment_words = 8

allow_missing_defaults = true

always = false

This configuration file sets that en is the default language (so this is the language that will be checked for comments, etc. and all tests will run relative to it). Then it sets various settings for each test. Every instance of [something_here] specifies that the following settings are for that test. For example, the test has_comments will now make sure that not only are there comments, but that they are at least 25 characters in length and 8 words in length.

You can now load in your configuration:

from localizationkit import Configuration

configuration = Configuration.from_file("/path/to/config.toml")

Localization Collections

Now we need to prepare the strings that will go in. Here's how you can create an individual string:

from localizationkit import LocalizedString

my_string = LocalizedString("My string's key", "My string's value", "My string's comment", "en")

This creates a single string with a key, value and comment, with its language code set to en. Once you've created some more (usually for different languages too), you can bundle them into a collection:

from localizationkit import LocalizedCollection

collection = LocalizedCollection(list_of_my_strings)

Running the tests

At this point, you are ready to run the tests:

import localizationkit

results = localizationkit.run_tests(configuration, collection)

for result in results:
    if not result.succeeded():
        print("The following test failed:",
        print("Failures encountered:")
        for violation in result.violations:

Not running the tests

Some tests don't make sense for everyone. To skip a test you can add the following to your config file at the root:

blacklist = ["test_identifier_1", "test_identifier_2"]

Rule documentation

Most tests have configurable rules. If a rule is not specified, it will use the default instead.

Some tests are opt in only. These will be marked as such.

Comment Linebreaks

Identifier: comment_linebreaks Opt-In: true

Checks that comments for strings do not contain linebreaks. Comments which contain linebreaks can interfere with parsing in other tools such as dotstrings.

Comment Similarity

Identifier: comment_similarity

Checks the similarity between a comment and the string's value in the default language. This is achieved via difflib's SequenceMatcher. More details can be found here

Parameter Type Acceptable Values Default Details
maximum_similarity_ratio float Between 0 and 1 0.5 Set the maximum similarity ratio between the comment and the string value. The higher the value, the more similar they are. The longer the string the more accurate this will be.

Duplicate Keys

Identifier: duplicate_keys

Checks that there are no duplicate keys in the collection.

Parameter Type Acceptable Values Default Details
all_languages boolean true or false false Set to true to check that every language has unique keys, not just the default language.

Has Comments

Identifier: has_comments

Checks that strings have comments.

Note: Only languages that have Latin style scripts are really supported for the words check due to splitting on spaces to check.

Parameter Type Acceptable Values Default Details
minimum_comment_length int Any integer 30 Set the minimum allowable length for a comment. Set the value to negative to not check.
minimum_comment_words int Any integer 10 Set the minimum allowable number of words for a comment. Set the value to negative to not check.

Has Value

Identifier: has_value

Checks that strings have values. Since any value is enough for some strings, it simply makes sure that the string isn't None/null and isn't empty.

Parameter Type Acceptable Values Default Details
default_language_only boolean true or false false Set to true to only check the default language for missing values. Otherwise all languages will be checked.

Invalid Tokens

Identifier: invalid_tokens

Checks that all format tokens in a string are valid.

Note: This check is not language specific. It only works very broadly.

Key Length

Identifier: key_length

Checks the length of the keys.

Note: By default this test doesn't check anything. It needs to have parameters set to positive values to do anything.

Parameter Type Acceptable Values Default Details
minimum int Any integer -1 Set the minimum allowable length for a key. Set the value to negative to not check.
maximum int Any integer -1 Set the maximum allowable length for a key. Set the value to negative to not check.

Objective-C Alternative Tokens

Identifier: objectivec_alternative_tokens Opt-In: true

Checks that strings do not contain Objective-C style alternative position tokens.

Objective-C seems to be allows positional tokens of the form %1@ rather than %1$@. While not illegal, it is preferred that all tokens between languages are consistent so that tools don't experience unexpected failures, etc.

Placeholder token explanation

Identifier: placeholder_token_explanation Opt-In: true

Checks that if a placeholder is used in a string, the comment explicitly explains what it is replaced with.

Precondition: Each placeholder in the string and its explanation in comment is expected to follow token_position_identifiers rule.

Swift Interpolation

Identifier: swift_interpolation Opt-In: true

Checks that strings do not contain Swift style interpolation values since these cannot be localized.

Token Matching

Identifier: token_matching

Checks that the tokens in a string match across all languages. e.g. If your English string is "Hello %s" but your French string is "Bonjour", this would flag that there is a missing token in the French string.

Parameter Type Acceptable Values Default Details
allow_missing_defaults boolean true or false false Due to the way that automated localization works, usually there will be a default language, and then other translations will come in over time. If a translation is deleted, it isn't always deleted from all languages immediately. Setting this parameter to true will allow any strings in your non-default language to be ignored if that string is missing from your default language.

Token Position Identifiers

Identifier: token_position_identifiers

Check that each token has a position specifier with it. e.g. %s is not allowed, but %1$s is. Tokens can move around in different languages, so position specifiers are extremely important.

Parameter Type Acceptable Values Default Details
always boolean true or false false If a string only has a single token, it doesn't need a position specifier. Set this to true to require it even in those cases.


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This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.

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