Expand Hypothesis and edge-case tests for elections, strategies, and methods

[endolith]

Summary

Adds property-based and explicit edge-case tests so tie-breaking, degenerate ballots, and spatial corner cases are exercised beyond line coverage alone.

Elections (test_elections.py)

• Hypothesis checks shapes and value ranges for random_utilities, valid permutations for impartial_culture, and finite outputs for normal_electorate (with constraints so the correlation scaling stays real).
• normed_dist_utilities: when every voter has distinct nearest/farthest distances, utilities stay in [0, 1] with correct row min/max; when two candidates share the same coordinates, documents current nan behavior from 0/0 normalization.

Strategies (test_strategies.py)

• honest_rankings: ballots remain permutations; constant utilities tie-break toward higher candidate ids first (NumPy argsort behavior).
• approval_optimal: all-equal utilities yield no approvals; every approval implies strictly above the row mean.
• vote_for_k: with strictly ordered utilities per row, each ballot has exactly k approvals.
• honest_normed_scores: explicit all-equal case; property test perturbs rows slightly so min/max normalization is well-defined without heavy assume filtering.

Condorcet / pairwise (test_condorcet.py)

• Hypothesis test_ranked_election_to_matrix (shape, diagonal, min/max bounds) unchanged in intent alongside new tests.
• Pairwise matrix: for i < j, M[i,j] + M[j,i] == n_voters.
• Any Condorcet winner strictly beats every other candidate pairwise.

Methods (test_methods.py)

• Black’s method matches the Condorcet winner when one exists, otherwise the Borda result (default tiebreaker behavior).
• SNTV with n=1 and tiebreaker='order' agrees with FPTP with the same tiebreaker (including None when both are tied).
• Hypothesis: ranked methods return a candidate index or None as appropriate; utility_winner(..., 'order') matches argmax of column sums.
• Explicit ties: utility_winner with two-way total tie; combined_approval with symmetric +1/-1 ballots.

  

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.31%. Comparing base (8a7213f) to head (ac8acc3).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #49   +/-   ##
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  Coverage   96.31%   96.31%           
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  Files          19       19           
  Lines         489      489           
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  Hits          471      471           
  Misses         18       18           

Flag	Coverage Δ
no-numba	95.50% <ø> (ø)
numba	89.16% <ø> (ø)

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