fix: add support for dynamic imports

lib/util/Graph.test.ts

@@ -0,0 +1,47 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { Graph } from './Graph.js';
+
+describe('Graph', () => {
+  it('should add edges correctly', () => {
+    const graph = new Graph();
+    graph.addEdge('A', 'B');
+    graph.addEdge('A', 'C');
+
+    assert.equal(graph.vertexes.size, 3);
+    assert.deepEqual(graph.vertexes.get('A')?.to, new Set(['B', 'C']));
+    assert.deepEqual(graph.vertexes.get('B')?.from, new Set(['A']));
+    assert.deepEqual(graph.vertexes.get('C')?.from, new Set(['A']));
+  });
+
+  it('should delete vertex correctly', () => {
+    const graph = new Graph();
+    graph.addEdge('A', 'B');
+    graph.addEdge('A', 'C');
+    graph.addEdge('B', 'C');
+
+    graph.deleteVertex('A');
+
+    assert.equal(graph.vertexes.size, 2);
+    assert.equal(graph.vertexes.has('A'), false);
+    assert.deepEqual(graph.vertexes.get('B')?.to, new Set(['C']));
+    assert.deepEqual(graph.vertexes.get('C')?.from, new Set(['B']));
+  });
+
+  it('should remove vertexes without any edges', () => {
+    const graph = new Graph();
+    graph.addEdge('A', 'B');
+    graph.addEdge('A', 'C');
+    graph.addEdge('B', 'C');
+    graph.deleteVertex('B');
+
+    assert.equal(graph.vertexes.size, 2);
+    assert.equal(graph.vertexes.has('B'), false);
+    assert.equal(graph.vertexes.has('A'), true);
+    assert.equal(graph.vertexes.has('C'), true);
+    assert.deepEqual(graph.vertexes.get('A')?.to, new Set(['C']));
+    assert.deepEqual(graph.vertexes.get('A')?.from.size, 0);
+    assert.equal(graph.vertexes.get('C')?.to.size, 0);
+    assert.deepEqual(graph.vertexes.get('C')?.from, new Set(['A']));
+  });
+});

lib/util/Graph.ts

@@ -0,0 +1,61 @@
+export class Graph {
+  vertexes = new Map<string, { to: Set<string>; from: Set<string> }>();
+
+  private addVertex(vertex: string) {
+    const selected = this.vertexes.get(vertex);
+    if (selected) {
+      return selected;
+    }
+
+    const created = { to: new Set<string>(), from: new Set<string>() };
+
+    this.vertexes.set(vertex, created);
+
+    return created;
+  }
+
+  deleteVertex(vertex: string) {
+    const selected = this.vertexes.get(vertex);
+
+    if (!selected) {
+      return;
+    }
+
+    for (const v of selected.to) {
+      const target = this.vertexes.get(v);
+
+      if (!target) {
+        continue;
+      }
+
+      target.from.delete(vertex);
+
+      if (target.from.size === 0 && target.to.size === 0) {
+        this.vertexes.delete(v);
+      }
+    }
+
+    for (const v of selected.from) {
+      const target = this.vertexes.get(v);
+
+      if (!target) {
+        continue;
+      }
+
+      target.to.delete(vertex);
+
+      if (target.from.size === 0 && target.to.size === 0) {
+        this.vertexes.delete(v);
+      }
+    }
+
+    this.vertexes.delete(vertex);
+  }
+
+  addEdge(source: string, destination: string): void {
+    const s = this.addVertex(source);
+    const d = this.addVertex(destination);
+    s.to.add(destination);
+    d.from.add(source);
+  }
+}

lib/util/collectDynamicImports.test.ts

@@ -0,0 +1,58 @@
+import { describe, it } from 'node:test';
+import { setup } from '../../test/helpers/setup.js';
+import { collectDynamicImports } from './collectDynamicImports.js';
+import ts from 'typescript';
+import assert from 'node:assert/strict';
+
+const getProgram = (languageService: ts.LanguageService) => {
+  const program = languageService.getProgram();
+
+  if (!program) {
+    throw new Error('Program not found');
+  }
+
+  return program;
+};
+
+describe('collectDynamicImports', () => {
+  it('should return a graph of dynamic imports', () => {
+    const { languageService, fileService } = setup();
+    fileService.set('/app/main.ts', `import('./a.js');`);
+    fileService.set('/app/a.ts', `export const a = 'a';`);
+
+    const program = getProgram(languageService);
+
+    const graph = collectDynamicImports({
+      fileService,
+      program,
+    });
+
+    assert.equal(graph.vertexes.size, 2);
+    assert.equal(graph.vertexes.has('/app/main.ts'), true);
+    assert.equal(graph.vertexes.has('/app/a.ts'), true);
+    assert.equal(graph.vertexes.get('/app/main.ts')?.to.size, 1);
+    assert.equal(graph.vertexes.get('/app/main.ts')?.to.has('/app/a.ts'), true);
+    assert.equal(graph.vertexes.get('/app/main.ts')?.from.size, 0);
+    assert.equal(graph.vertexes.get('/app/a.ts')?.from.size, 1);
+    assert.equal(
+      graph.vertexes.get('/app/a.ts')?.from.has('/app/main.ts'),
+      true,
+    );
+    assert.equal(graph.vertexes.get('/app/a.ts')?.to.size, 0);
+  });
+
+  it('should return an empty graph if no dynamic imports are found', () => {
+    const { languageService, fileService } = setup();
+    fileService.set('/app/main.ts', `import { a } from './a.js';`);
+    fileService.set('/app/a.ts', `export const a = 'a';`);
+
+    const program = getProgram(languageService);
+
+    const graph = collectDynamicImports({
+      fileService,
+      program,
+    });
+
+    assert.equal(graph.vertexes.size, 0);
+  });
+});

lib/util/collectDynamicImports.ts

@@ -0,0 +1,50 @@
+import ts from 'typescript';
+import { getFileFromModuleSpecifierText } from './getFileFromModuleSpecifierText.js';
+import { FileService } from './FileService.js';
+import { Graph } from './Graph.js';
+
+export const collectDynamicImports = ({
+  program,
+  fileService,
+}: {
+  program: ts.Program;
+  fileService: FileService;
+}) => {
+  const graph = new Graph();
+  const files = fileService.getFileNames();
+  for (const file of files) {
+    const sourceFile = program.getSourceFile(file);
+
+    if (!sourceFile) {
+      continue;
+    }
+
+    const visit = (node: ts.Node) => {
+      if (
+        ts.isCallExpression(node) &&
+        node.expression.kind === ts.SyntaxKind.ImportKeyword &&
+        node.arguments[0] &&
+        ts.isStringLiteral(node.arguments[0])
+      ) {
+        const file = getFileFromModuleSpecifierText({
+          specifier: node.arguments[0].text,
+          program,
+          fileService,
+          fileName: sourceFile.fileName,
+        });
+
+        if (file) {
+          graph.addEdge(sourceFile.fileName, file);
+        }
+
+        return;
+      }
+
+      node.forEachChild(visit);
+    };
+
+    sourceFile.forEachChild(visit);
+  }
+
+  return graph;
+};

lib/util/getFileFromModuleSpecifierText.ts

@@ -0,0 +1,22 @@
+import ts from 'typescript';
+import { FileService } from './FileService.js';
+
+export const getFileFromModuleSpecifierText = ({
+  specifier,
+  fileName,
+  program,
+  fileService,
+}: {
+  specifier: string;
+  fileName: string;
+  program: ts.Program;
+  fileService: FileService;
+}) =>
+  ts.resolveModuleName(specifier, fileName, program.getCompilerOptions(), {
+    fileExists(fileName) {
+      return fileService.exists(fileName);
+    },
+    readFile(fileName) {
+      return fileService.get(fileName);
+    },
+  }).resolvedModule?.resolvedFileName;

lib/util/removeUnusedExport.test.ts

@@ -1,36 +1,7 @@
 import { describe, it } from 'node:test';
-import { MemoryFileService } from './MemoryFileService.js';
-import ts from 'typescript';
 import assert from 'node:assert/strict';
 import { removeUnusedExport } from './removeUnusedExport.js';
-
-const setup = () => {
-  const fileService = new MemoryFileService();
-
-  const languageService = ts.createLanguageService({
-    getCompilationSettings() {
-      return {};
-    },
-    getScriptFileNames() {
-      return fileService.getFileNames();
-    },
-    getScriptVersion(fileName) {
-      return fileService.getVersion(fileName);
-    },
-    getScriptSnapshot(fileName) {
-      return ts.ScriptSnapshot.fromString(fileService.get(fileName));
-    },
-    getCurrentDirectory: () => '.',
-
-    getDefaultLibFileName(options) {
-      return ts.getDefaultLibFileName(options);
-    },
-    fileExists: (name) => fileService.exists(name),
-    readFile: (name) => fileService.get(name),
-  });
-
-  return { languageService, fileService };
-};
+import { setup } from '../../test/helpers/setup.js';
 
 describe('removeUnusedExport', () => {
   describe('variable statement', () => {
@@ -832,6 +803,28 @@ const b: B = {};`,
     );
   });
 
+  describe('dynamic import', () => {
+    it('should not remove export if its used in dynamic import', () => {
+      const { languageService, fileService } = setup();
+      fileService.set(
+        '/app/main.ts',
+        `import('./a.js');
+import('./b.js');`,
+      );
+      fileService.set('/app/a.ts', `export const a = 'a';`);
+      fileService.set('/app/b.ts', `export default 'b';`);
+
+      removeUnusedExport({
+        languageService,
+        fileService,
+        targetFile: ['/app/a.ts', '/app/b.ts'],
+      });
+
+      assert.equal(fileService.get('/app/a.ts'), `export const a = 'a';`);
+      assert.equal(fileService.get('/app/b.ts'), `export default 'b';`);
+    });
+  });
+
   describe('deleteUnusedFile', () => {
     it('should not remove file if some exports are used in other files', () => {
       const { languageService, fileService } = setup();

lib/util/removeUnusedExport.ts

@@ -7,6 +7,8 @@ import {
   fixIdDeleteImports,
 } from './applyCodeFix.js';
 import { EditTracker } from './EditTracker.js';
+import { getFileFromModuleSpecifierText } from './getFileFromModuleSpecifierText.js';
+import { collectDynamicImports } from './collectDynamicImports.js';
 
 const findFirstNodeOfKind = (root: ts.Node, kind: ts.SyntaxKind) => {
   let result: ts.Node | undefined;
@@ -151,26 +153,6 @@ const getReexportInFile = (file: ts.SourceFile) => {
   return result;
 };
 
-const getFileFromModuleSpecifierText = ({
-  specifier,
-  fileName,
-  program,
-  fileService,
-}: {
-  specifier: string;
-  fileName: string;
-  program: ts.Program;
-  fileService: FileService;
-}) =>
-  ts.resolveModuleName(specifier, fileName, program.getCompilerOptions(), {
-    fileExists(fileName) {
-      return fileService.exists(fileName);
-    },
-    readFile(fileName) {
-      return fileService.get(fileName);
-    },
-  }).resolvedModule?.resolvedFileName;
-
 const getAncestorFiles = (
   node: ts.ExportSpecifier,
   references: ts.ReferencedSymbol[],
@@ -546,6 +528,9 @@ export const removeUnusedExport = ({
     throw new Error('program not found');
   }
 
+  // because ts.LanguageService.findReferences doesn't work with dynamic imports, we need to collect them manually
+  const dynamicImports = collectDynamicImports({ program, fileService });
+
   for (const file of Array.isArray(targetFile) ? targetFile : [targetFile]) {
     const sourceFile = program.getSourceFile(file);
 
@@ -555,6 +540,13 @@ export const removeUnusedExport = ({
 
     editTracker.start(file, sourceFile.getFullText());
 
+    const dynamicImport = dynamicImports.vertexes.get(file);
+
+    if (dynamicImport && dynamicImport.from.size > 0) {
+      editTracker.end(file);
+      continue;
+    }
+
     let content = fileService.get(file);
     let isUsed = false;
 
@@ -581,6 +573,7 @@ export const removeUnusedExport = ({
     if (!isUsed && deleteUnusedFile) {
       fileService.delete(file);
       editTracker.delete(file);
+      dynamicImports.deleteVertex(file);
 
       continue;
     }