walk and morph functions to preserve import statement along with tests

Author: m-Bilal

src/app/parser/typescript/morph.test.ts

@@ -137,6 +137,40 @@ describe("morph::user-defined-types", async () => {
   }
 });
 
+const importDeclarationsTests: TestCase[] = [
+  {
+    name: "Preserve Imports",
+    directory: "./test-data/morph-tests/imports/",
+  }
+];
+
+describe("morph::import-declarations", async () => {
+  for (const testCase of importDeclarationsTests) {
+    before(function () {
+      setupTest(testCase);
+    });
+
+    it(testCase.name, async () => {
+      morph.preserveImportDeclarations(
+        testCase.staleSourceFile!,
+        testCase.freshSourceFile!,
+      );
+
+      const gotStr = await prettier.format(
+        testCase.freshSourceFile?.getFullText()!,
+        {
+          parser: "typescript",
+        },
+      );
+
+      assert.equal(testCase.mergedFileContents, gotStr);
+
+      // uncomment to update merged golden file
+      // fs.writeFileSync(path.resolve(testCase.directory, "merged.ts"), gotStr);
+    });
+  }
+});
+
 function setupTest(testCase: TestCase) {
   testCase.directory = path.resolve(__dirname, testCase.directory);
   const staleProject = new ts.Project();

src/app/parser/typescript/morph.ts

@@ -65,6 +65,29 @@ export function preserveSavedClasses(
   preserveNode(staleSourceClasses, freshSourceClasses, freshTsSourceFile);
 }
 
+export function preserveImportDeclarations(
+  staleTsSourceFile: tsMorph.SourceFile,
+  freshTsSourceFile: tsMorph.SourceFile,
+) {
+  const staleSourceImports = walk.getAllImportDeclarationsMap(staleTsSourceFile);
+  const freshSourceImports = walk.getAllImportDeclarationsMap(freshTsSourceFile);
+
+  staleSourceImports.forEach((staleNode, staleNodeName) => {
+    const freshNode = freshSourceImports.get(staleNodeName);
+
+    if (freshNode) {
+      // this import statement already exists in the fresh source file
+      // replace it with the stale import statement
+      freshNode.replaceWithText(staleNode.getText());
+    } else {
+      // this import statement does not exist in the fresh source file
+      // add it to the fresh source
+      freshTsSourceFile.insertStatements(0, staleNode.getText());
+    }
+  })
+}
+
+
 /**
  * this function preservers nodes that are marked with `@save` annotation in the stale source file
  * if a saved node is missing in the fresh source file, it will be copied to it

src/app/parser/typescript/test-data/morph-tests/imports/a.ts

@@ -0,0 +1,3 @@
+export function helloWorld() {
+    return "hello world";
+}

src/app/parser/typescript/test-data/morph-tests/imports/fresh.ts

@@ -0,0 +1,5 @@
+import * as a from "./a";
+import * as tsMorph from "ts-morph";
+import { exit } from "process";
+import { SemVer } from "semver";
+

src/app/parser/typescript/test-data/morph-tests/imports/merged.ts

@@ -0,0 +1,13 @@
+import * as fs from "fs";
+import * as path from "path";
+import { helloWorld } from "./a";
+import {
+  SourceFile,
+  SourceFileEmitOptions,
+  NamespaceImport,
+  NamedImports,
+  NamedExports,
+  ModuleDeclaration,
+} from "ts-morph";
+import * as process from "process";
+import { SemVer } from "semver";

src/app/parser/typescript/test-data/morph-tests/imports/stale.ts

@@ -0,0 +1,14 @@
+import { helloWorld } from "./a";
+import {
+  SourceFile,
+  SourceFileEmitOptions,
+  NamespaceImport,
+  NamedImports,
+  NamedExports,
+  ModuleDeclaration,
+} from "ts-morph";
+import * as process from "process";
+import * as path from "path";
+import * as fs from "fs";
+
+export function hello() {}

src/app/parser/typescript/test-data/walk-tests/imports/a.ts

@@ -0,0 +1,3 @@
+export function helloWorld() {
+    return "hello world";
+}

src/app/parser/typescript/test-data/walk-tests/imports/got.ts

@@ -0,0 +1,8 @@
+import * as a from "./a";
+import * as tsMorph from "ts-morph";
+import { exit } from "process";
+import { SemVer } from "semver";
+import * as path from "path";
+import * as fs from "fs";
+
+export function hello() {}

src/app/parser/typescript/test-data/walk-tests/imports/want.json

@@ -0,0 +1,8 @@
+{
+  "\"./a\"": "import * as a from \"./a\";",
+  "\"ts-morph\"": "import * as tsMorph from \"ts-morph\";",
+  "\"process\"": "import { exit } from \"process\";",
+  "\"semver\"": "import { SemVer } from \"semver\";",
+  "\"path\"": "import * as path from \"path\";",
+  "\"fs\"": "import * as fs from \"fs\";"
+}

src/app/parser/typescript/walk.test.ts

@@ -136,6 +136,36 @@ describe("walk::user-defined-types-tests", async () => {
   }
 });
 
+const importDeclarationsTests: TestCase[] = [{  
+  name: "getImportDeclarationTests",
+  testFile: "./test-data/walk-tests/imports/got.ts",
+  goldenFile: "./test-data/walk-tests/imports/want.json",
+}];
+
+describe("walk::import-declarations-tests", async () => {
+  for (const testCase of importDeclarationsTests) {
+    before(function () {
+      setupTestCase(testCase);
+    });
+
+    it(`${testCase.name}`, function () {
+      const project = new ts.Project();
+      const tsSourceFile = project.addSourceFileAtPath(testCase.testFile);
+
+      const importsMap = tsWalk.getAllImportDeclarationsMap(tsSourceFile);
+      const gotImports: Record<string, string> = {};
+
+      importsMap.forEach((importDeclaration, importName) => {
+        gotImports[importName] = importDeclaration.getText();
+      });
+
+      assert.deepEqual(testCase.goldenFileContents, gotImports);
+
+      // writeFileSync(testCase.goldenFile, JSON.stringify(gotImports, null, 2));
+    });
+  }
+});
+
 function setupTestCase(testCase: TestCase) {
   testCase.testFile = path.resolve(__dirname, testCase.testFile);
   testCase.goldenFile = path.resolve(__dirname, testCase.goldenFile);