feat(utils): generate random identifiers (#85)

foca/__init__.py

@@ -1 +1 @@
-__version__ = '0.5.0'
+__version__ = '0.6.0'

foca/utils/misc.py

@@ -0,0 +1,41 @@
+"""Miscellaneous utility functions."""
+
+from random import choice
+import string
+
+
+def generate_id(
+    charset: str = ''.join([string.ascii_letters, string.digits]),
+    length: int = 6
+) -> str:
+    """Generate random string based on allowed set of characters.
+
+    Args:
+        charset: A string of allowed characters or an expression evaluating to
+            a string of allowed characters.
+        length: Length of returned string.
+
+    Returns:
+        Random string of specified length and composed of defined set of
+        allowed characters.
+
+    Raises:
+        TypeError: Raised if 'charset' cannot be evaluated to a string or if
+            'length' is not a positive integer.
+    """
+    try:
+        charset = eval(charset)
+    except (NameError, SyntaxError):
+        pass
+    except Exception as e:
+        raise TypeError(f"Could not evaluate 'charset': {charset}") from e
+    if not isinstance(charset, str) or charset == "":
+        raise TypeError(
+            f"Could not evaluate 'charset' to non-empty string: {charset}"
+        )
+    if not isinstance(length, int) or not length > 0:
+        raise TypeError(
+            f"Argument to 'length' is not a positive integer: {length}"
+        )
+    charset = ''.join(sorted(set(charset)))
+    return ''.join(choice(charset) for __ in range(length))

tests/utils/test_misc.py

@@ -0,0 +1,70 @@
+"""Tests for miscellaneous utility functions."""
+
+import string
+
+import pytest
+
+from foca.utils.misc import generate_id
+
+
+class TestGenerateId:
+
+    def test_default(self):
+        """Use only default arguments."""
+        res = generate_id()
+        assert isinstance(res, str)
+
+    def test_charset_literal_string(self):
+        """Argument to `charset` is non-default literal string."""
+        charset = string.digits
+        res = generate_id(charset=charset)
+        assert set(res) <= set(string.digits)
+
+    def test_charset_literal_string_duplicates(self):
+        """Argument to `charset` is non-default literal string with duplicates.
+        """
+        charset = string.digits + string.digits
+        res = generate_id(charset=charset)
+        assert set(res) <= set(string.digits)
+
+    def test_charset_evaluates_to_string(self):
+        """Argument to `charset` evaluates to string."""
+        charset = "''.join([c for c in string.digits])"
+        res = generate_id(charset=charset)
+        assert set(res) <= set(string.digits)
+
+    def test_charset_evaluates_to_empty_string(self):
+        """Argument to `charset` evaluates to non-string."""
+        charset = "''.join([])"
+        with pytest.raises(TypeError):
+            generate_id(charset=charset)
+
+    def test_charset_evaluates_to_non_string(self):
+        """Argument to `charset` evaluates to non-string."""
+        charset = "1"
+        with pytest.raises(TypeError):
+            generate_id(charset=charset)
+
+    def test_evaluation_error(self):
+        """Evaulation of `length` raises an exception."""
+        charset = int
+        with pytest.raises(TypeError):
+            generate_id(charset=charset)  # type: ignore
+
+    def test_length(self):
+        """Non-default argument to `length`."""
+        length = 1
+        res = generate_id(length=length)
+        assert len(res) == length
+
+    def test_length_not_int(self):
+        """Argument to `length` is not an integer."""
+        length = ""
+        with pytest.raises(TypeError):
+            generate_id(length=length)  # type: ignore
+
+    def test_length_not_positive(self):
+        """Argument to `length` is not a positive integer."""
+        length = -1
+        with pytest.raises(TypeError):
+            generate_id(length=length)