Fix js-experimental ImportMap by not rendering empty statements

.changeset/tiny-ducks-love.md

@@ -0,0 +1,5 @@
+---
+'@metaplex-foundation/kinobi': patch
+---
+
+Fix js-experimental ImportMap by not rendering empty statements

src/renderers/js-experimental/ImportMap.ts

@@ -36,8 +36,11 @@ export class ImportMap {
     new Map();
 
   add(module: ImportFrom, imports: string | string[] | Set<string>): ImportMap {
+    const newImports = new Set(
+      typeof imports === 'string' ? [imports] : imports
+    );
+    if (newImports.size === 0) return this;
     const currentImports = this._imports.get(module) ?? new Set();
-    const newImports = typeof imports === 'string' ? [imports] : imports;
     newImports.forEach((i) => currentImports.add(i));
     this._imports.set(module, currentImports);
     return this;
@@ -47,8 +50,11 @@ export class ImportMap {
     module: ImportFrom,
     imports: string | string[] | Set<string>
   ): ImportMap {
+    const importsToRemove = new Set(
+      typeof imports === 'string' ? [imports] : imports
+    );
+    if (importsToRemove.size === 0) return this;
     const currentImports = this._imports.get(module) ?? new Set();
-    const importsToRemove = typeof imports === 'string' ? [imports] : imports;
     importsToRemove.forEach((i) => currentImports.delete(i));
     if (currentImports.size === 0) {
       this._imports.delete(module);
@@ -93,7 +99,7 @@ export class ImportMap {
     return this._imports.size === 0;
   }
 
-  toString(dependencies: Record<ImportFrom, string>): string {
+  toString(dependencies: Record<ImportFrom, string> = {}): string {
     const dependencyMap = { ...DEFAULT_MODULE_MAP, ...dependencies };
     const importStatements = [...this._imports.entries()]
       .map(([module, imports]) => {

test/renderers/js-experimental/ImportMap.test.ts

@@ -0,0 +1,77 @@
+import test from 'ava';
+import { ImportMap } from '../../../src/renderers/js-experimental/ImportMap';
+
+test('it renders JavaScript import statements', (t) => {
+  // Given an import map with 3 imports from 2 sources.
+  const importMap = new ImportMap()
+    .add('@solana/addresses', ['getAddressEncoder', 'Address'])
+    .add('@solana/transactions', 'Transaction');
+
+  // When we render it.
+  const importStatements = importMap.toString();
+
+  // Then we expect the following import statements.
+  t.is(
+    importStatements,
+    "import { Address, getAddressEncoder } from '@solana/addresses';\n" +
+      "import { Transaction } from '@solana/transactions';"
+  );
+});
+
+test('it renders JavaScript import aliases', (t) => {
+  // Given an import map with an import alias.
+  const importMap = new ImportMap()
+    .add('@solana/addresses', 'Address')
+    .addAlias('@solana/addresses', 'Address', 'SolanaAddress');
+
+  // When we render it.
+  const importStatements = importMap.toString();
+
+  // Then we expect the following import statement.
+  t.is(
+    importStatements,
+    "import { Address as SolanaAddress } from '@solana/addresses';"
+  );
+});
+
+test('it offers some default dependency mappings', (t) => {
+  // Given an import map with some recognized dependency keys.
+  const importMap = new ImportMap()
+    .add('solanaAddresses', 'Address')
+    .add('solanaCodecsCore', 'Codec')
+    .add('generatedTypes', 'MyType')
+    .add('shared', 'myHelper')
+    .add('hooked', 'MyCustomType');
+
+  // When we render it.
+  const importStatements = importMap.toString();
+
+  // Then we expect the following import statements.
+  t.is(
+    importStatements,
+    "import { Address } from '@solana/addresses';\n" +
+      "import { Codec } from '@solana/codecs-core';\n" +
+      "import { MyCustomType } from '../../hooked';\n" +
+      "import { myHelper } from '../shared';\n" +
+      "import { MyType } from '../types';"
+  );
+});
+
+test('it supports custom dependency mappings', (t) => {
+  // Given an import map with some custom dependency keys.
+  const importMap = new ImportMap().add('myDependency', 'MyType');
+
+  // When we render it whilst providing custom dependency mappings.
+  const importStatements = importMap.toString({
+    myDependency: 'my/custom/path',
+  });
+
+  // Then we expect the following import statement.
+  t.is(importStatements, "import { MyType } from 'my/custom/path';");
+});
+
+test('it does not render empty import statements', (t) => {
+  t.is(new ImportMap().toString(), '');
+  t.is(new ImportMap().add('shared', []).toString(), '');
+  t.is(new ImportMap().addAlias('shared', 'Foo', 'Bar').toString(), '');
+});