perf(ban-dependencies): look up import paths instead of scanning all mappings

src/rules/ban-dependencies.test.ts

@@ -31,6 +31,9 @@ ruleTester.run('ban-dependencies', banDependencies, {
     {
       code: `import foo from 'unknown-module';`
     },
+    {
+      code: `import foo from 'unknown-module/subpath';`
+    },
     {
       code: `const foo = require('unknown-module');`
     },
@@ -63,6 +66,15 @@ ruleTester.run('ban-dependencies', banDependencies, {
         }
       ]
     },
+    {
+      code: `import foo from 'is-nan/subpath';`,
+      options: [
+        {
+          presets: ['native'],
+          allowed: ['is-nan']
+        }
+      ]
+    },
     {
       code: `import foo from 'oogabooga';`,
       options: [
@@ -138,6 +150,21 @@ ruleTester.run('ban-dependencies', banDependencies, {
         }
       ]
     },
+    {
+      code: `import foo from 'is-number/subpath';`,
+      errors: [
+        {
+          line: 1,
+          column: 1,
+          messageId: 'simpleReplacement',
+          data: {
+            name: 'is-number',
+            description:
+              'You can check if a value is a number by using `typeof` or coercing it to a number and using `Number.isFinite`.'
+          }
+        }
+      ]
+    },
     {
       code: `const foo = await import('is-number');`,
       errors: [
@@ -224,6 +251,46 @@ ruleTester.run('ban-dependencies', banDependencies, {
         }
       ]
     },
+    {
+      code: `import foo from 'oogabooga/subpath/deep';`,
+      options: [
+        {
+          modules: ['oogabooga', 'oogabooga/subpath']
+        }
+      ],
+      errors: [
+        {
+          line: 1,
+          column: 1,
+          messageId: 'removalReplacement',
+          data: {
+            name: 'oogabooga/subpath',
+            description:
+              'This module is disallowed and should be replaced with an alternative.'
+          }
+        }
+      ]
+    },
+    {
+      code: `import foo from 'oogabooga/subpath/deep';`,
+      options: [
+        {
+          modules: ['oogabooga/subpath', 'oogabooga']
+        }
+      ],
+      errors: [
+        {
+          line: 1,
+          column: 1,
+          messageId: 'removalReplacement',
+          data: {
+            name: 'oogabooga/subpath',
+            description:
+              'This module is disallowed and should be replaced with an alternative.'
+          }
+        }
+      ]
+    },
     {
       code: `import foo from 'object-is';`,
       options: [

src/rules/ban-dependencies.ts

@@ -50,6 +50,28 @@ function hasMatchingEngine(
   return closestPackageSatisfiesNodeVersion(context, engineRange);
 }
 
+/**
+ * Finds the mapping for `source` or its closest parent path. For example,
+ * `foo/bar/baz` checks `foo/bar/baz`, then `foo/bar`, then `foo`.
+ */
+function findMapping(
+  mappings: ManifestModule['mappings'],
+  source: string
+): ModuleReplacementMapping | undefined {
+  // `end` only decreases, so the loop always terminates.
+  for (
+    let end = source.length;
+    end > 0;
+    end = source.lastIndexOf('/', end - 1)
+  ) {
+    const moduleName = source.slice(0, end);
+    if (Object.hasOwn(mappings, moduleName)) {
+      return mappings[moduleName];
+    }
+  }
+  return undefined;
+}
+
 /**
  * Callback used for the replacement listener
  */
@@ -70,16 +92,16 @@ function replacementListenerCallback(
   let currentMapping: ModuleReplacementMapping | undefined;
 
   for (const manifest of manifests) {
-    for (const [moduleName, mapping] of Object.entries(manifest.mappings)) {
-      if (moduleName === source || source.startsWith(`${moduleName}/`)) {
-        currentMapping = mapping;
-        for (const replacementId of mapping.replacements) {
-          const replacement = manifest.replacements[replacementId];
-          if (replacement) {
-            replacements.push(replacement);
-          }
-        }
-        break;
+    const mapping = findMapping(manifest.mappings, source);
+    if (!mapping) {
+      continue;
+    }
+
+    currentMapping = mapping;
+    for (const replacementId of mapping.replacements) {
+      const replacement = manifest.replacements[replacementId];
+      if (replacement) {
+        replacements.push(replacement);
       }
     }
   }