Harden tailwind class difference classification

Make comparison outcome handling explicit so each classify result is mapped to a known kind, and token-multiset cases now include formatter token-loss symmetry checks to avoid false exact matches.

Author: praveenperera

tests/tailwind-compare/compare.mjs

@@ -357,31 +357,19 @@ function compareAttribute(
   const kind = classifyDifference(comparison);
   if (kind === "token-multiset") {
     summary.extractionMismatch += 1;
-    pending.push({
-      attribute,
-      ...comparison,
-      kind,
-      path: candidate.path,
-    });
-    return;
-  }
-  if (kind === "prettier-nonconvergent") {
+  } else if (kind === "prettier-nonconvergent") {
     summary.prettierNonconvergent += 1;
-    pending.push({
-      attribute,
-      ...comparison,
-      kind,
-      path: candidate.path,
-    });
-    return;
-  }
-  if (kind === "exact") {
+  } else if (kind === "exact") {
     summary.exact += 1;
     return;
+  } else if (kind !== "order-difference") {
+    throw new Error(`Unexpected comparison kind: ${kind}`);
   }
+
   pending.push({
     attribute,
     ...comparison,
+    kind,
     path: candidate.path,
   });
 }
@@ -505,7 +493,7 @@ async function compareCandidates(configuration, candidates) {
   }
 
   const orderDifferences = pending.filter(
-    (detail) => detail.kind === undefined,
+    (detail) => detail.kind === "order-difference",
   );
   let known;
   try {

tests/tailwind-compare/lib.mjs

@@ -217,9 +217,9 @@ export function classifyDifference(comparison, known) {
   } = comparison;
   if (
     !sameMultiset(original, scrambled) ||
-    ![prettierScrambled, rustywind].every((tokens) =>
-      sameMultiset(prettierOriginal, tokens),
-    )
+    !sameMultiset(original, prettierOriginal) ||
+    !sameMultiset(scrambled, prettierScrambled) ||
+    !sameMultiset(scrambled, rustywind)
   ) {
     return "token-multiset";
   }

tests/tailwind-compare/test/lib.test.mjs

@@ -189,7 +189,7 @@ test("rejects order classification without a result for every token", () => {
   );
 });
 
-test("allows convergent duplicate removal by both formatters", () => {
+test("rejects convergent token removal by both formatters", () => {
   assert.equal(
     classifyDifference({
       original: ["rtl:mr-0", "flex", "rtl:mr-0"],
@@ -198,7 +198,7 @@ test("allows convergent duplicate removal by both formatters", () => {
       prettierScrambled: ["flex", "rtl:mr-0"],
       rustywind: ["flex", "rtl:mr-0"],
     }),
-    "exact",
+    "token-multiset",
   );
 });