RhymePad: phonetic rhyme scratchpad for poets & rappers

FastAPI backend with CMU-dict rhyme detection (perfect, internal,
multisyllabic slant, consonance, multi-word phrases), g2p fallback for
unknown words, rhyme/synonym lookup, draggable stanza reordering,
localStorage drafts, and synthesized beats. 19 regression tests drawn
from real verses (Wayne, Em, Kanye).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_rhymes.py

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+"""Regression suite for RhymePad's rhyme detection.
+
+Every case here came from a real verse that exposed a gap during
+development — Lil Wayne ("6 Foot 7 Foot"), Eminem ("Godzilla"),
+Kanye ("Power"), and assorted hand-rolled edge cases.
+"""
+
+from collections import defaultdict
+
+import pytest
+
+from app import Draft, analyze, lookup
+
+
+def groups(text: str) -> list[set[str]]:
+    """Rhyme groups as sets of (lowercased) highlighted spans."""
+    res = analyze(Draft(text=text))
+    by_gid = defaultdict(set)
+    for t in res["tokens"]:
+        by_gid[t["g"]].add(res["lines"][t["l"]][t["s"]:t["e"]].lower())
+    return list(by_gid.values())
+
+
+def group_with(text: str, *words: str) -> set[str]:
+    """The group containing words[0]; asserts all words share it."""
+    for g in groups(text):
+        if words[0].lower() in g:
+            missing = {w.lower() for w in words} - g
+            assert not missing, f"{missing} not grouped with {words[0]!r} in {g}"
+            return g
+    pytest.fail(f"{words[0]!r} not highlighted at all")
+
+
+def highlighted(text: str) -> set[str]:
+    gs = groups(text)
+    return set().union(*gs) if gs else set()
+
+
+def scheme(text: str) -> str:
+    return analyze(Draft(text=text))["stanzas"][0]["scheme"]
+
+
+# ---------------------------------------------------------------- perfect
+
+def test_perfect_end_rhymes():
+    text = ("I keep the cadence tucked beneath my tongue tonight\n"
+            "the city hums in amber under fading light\n"
+            "I trace a melody that never quite takes flight\n"
+            "and let the silence answer everything I write")
+    group_with(text, "tonight", "light", "flight", "write", "quite")
+    assert scheme(text) == "aaaa"
+
+
+def test_internal_perfect_rhymes():
+    text = ("no time to waste, I climb in haste and find my place\n"
+            "the rhythm shows, the river flows, wherever it goes")
+    group_with(text, "time", "climb")
+    group_with(text, "waste", "haste")
+    group_with(text, "shows", "flows", "goes")
+
+
+def test_say_weigh():
+    group_with("say this weigh that", "say", "weigh")
+
+
+def test_abab_scheme():
+    assert scheme("the cat\nso blue\na hat\nso true") == "abab"
+
+
+# ------------------------------------------------------------------ slant
+
+def test_end_slant_joins_existing_perfect_group():
+    # "time" (AY M) slant-joins the mind/find (AY N D) perfect group
+    text = ("the placement of creation\n"
+            "eternal precipice of mind\n"
+            "where it goes\n"
+            "i can't find the time")
+    group_with(text, "mind", "find", "time")
+    group_with(text, "placement", "creation")
+    assert scheme(text) == "abcb"
+
+
+def test_kanye_hours_power():
+    text = ("The clock's ticking, I just count the hours\n"
+            "Stop tripping, I'm tripping off the power")
+    group_with(text, "hours", "power")
+    group_with(text, "ticking", "tripping")
+    # the multi-word pass catches the full phrase pair too
+    group_with(text, "clock's ticking", "stop tripping")
+    assert scheme(text) == "aa"
+
+
+def test_reduced_vowel_merge_vodka_lasagna():
+    # AA + schwa, with different reduced vowels — the Wayne chain
+    text = ("vodka with a spritzer\n"
+            "real Gs move in silence like lasagna")
+    group_with(text, "vodka", "lasagna")
+
+
+def test_consonance_bliss_exist():
+    # vowel + first coda consonant (IH S), full codas differ;
+    # "whisps" is OOV and needs the g2p model
+    group_with("bliss whisps in darker nights exist",
+               "bliss", "whisps", "exist")
+
+
+# ------------------------------------------------- unknown words / repairs
+
+def test_compound_split_heresay_neigh():
+    text = ("the rhythm and the gotcha of the heresay\n"
+            "neigh")
+    group_with(text, "heresay", "neigh")
+
+
+def test_multiword_orange_door_hinge_porage():
+    text = ("an orange door hinge\n"
+            "porage")
+    group_with(text, "orange", "door hinge", "porage")
+
+
+def test_cmu_variant_get_rhymes_with_hit():
+    # CMU's secondary pronunciation of "get" is "git"
+    group_with("take the hit\nthat's what you get", "hit", "get")
+
+
+# ------------------------------------------------------------------ noise
+
+def test_no_transitive_chaining():
+    # peanuts rhymes with what's via one pronunciation (AH T S) and with
+    # people via another (IY + schwa) — the two groups must stay separate
+    text = ("So misunderstood, but what's a world without enigma?\n"
+            "You niggas are gelatin, peanuts to an elephant\n"
+            "Sleep is the cousin, what a fuckin' family picture\n"
+            "People say I'm borderline crazy, sorta, kinda\n"
+            "Woman of my dreams, I don't sleep, so I can't find her")
+    whats = group_with(text, "what's", "peanuts")
+    assert "sleep" not in whats and "people" not in whats
+    sleep = group_with(text, "sleep", "people")
+    assert "what's" not in sleep
+
+
+def test_filler_words_not_highlighted_midline():
+    text = ("I'm a monster and I'm heartless, I'm the king\n"
+            "and I'm the sting")
+    assert "i'm" not in highlighted(text)
+    group_with(text, "king", "sting")
+
+
+def test_em_counts_at_line_end_only():
+    text = ("Fill 'em with the venom and eliminate 'em\n"
+            "I told 'em owls fly, I Minute Maid 'em")
+    assert scheme(text) == "aa"  # ...ate 'em / Maid 'em
+    # but the mid-line 'em's stay dark
+    res = analyze(Draft(text=text))
+    em_tokens = [t for t in res["tokens"]
+                 if res["lines"][t["l"]][t["s"]:t["e"]].lower() == "em"]
+    assert all(t["end"] for t in em_tokens)
+
+
+def test_repeated_word_midline_is_not_a_rhyme():
+    assert highlighted("the fire burns the fire down") == set()
+
+
+# ----------------------------------------------------------------- lookup
+
+def test_lookup_rhymes():
+    words = {w["word"] for w in lookup("light", mode="rhyme")["words"]}
+    assert "night" in words and "tonight" in words
+    assert "light" not in words
+
+
+def test_lookup_near_rhymes_exclude_perfect():
+    words = {w["word"] for w in lookup("hold", mode="near")["words"]}
+    assert "home" in words      # shared vowel, different coda
+    assert "gold" not in words  # perfect rhymes live in the other mode
+
+
+# ------------------------------------------------------------------ shape
+
+def test_stanzas_and_legend():
+    res = analyze(Draft(text="the cat\nso blue\na hat\nso true"))
+    (st,) = res["stanzas"]
+    assert st["lines"] == [0, 1, 2, 3]
+    a, b = st["legend"][0], st["legend"][1]
+    assert a["ch"] == "a" and b["ch"] == "b"
+    assert a["color"] is not None and b["color"] is not None
+    assert a["color"] != b["color"]
+
+
+def test_blank_lines_split_stanzas():
+    res = analyze(Draft(text="the cat\na hat\n\nso blue\nso true"))
+    assert [s["scheme"] for s in res["stanzas"]] == ["aa", "aa"]