Port no-declare-current-package tslint->eslint

packages/dtslint/dt.json

@@ -1,7 +1,6 @@
 {
 	"extends": "./dtslint.json",
 	"rules": {
-		"no-declare-current-package": true,
 		"no-self-import": true,
 		"no-outside-dependencies": true,
 

packages/dtslint/src/rules/no-declare-current-package.ts

@@ -0,0 +1,42 @@
+import { getCommonDirectoryName, createRule } from "../util";
+import { ESLintUtils, AST_NODE_TYPES } from "@typescript-eslint/utils";
+const rule = createRule({
+  name: "no-declare-current-package",
+  defaultOptions: [],
+  meta: {
+    type: "problem",
+    docs: {
+      description: "Don't use an ambient module declaration of the current package; use a normal module.",
+      recommended: "error",
+    },
+    messages: {
+      noDeclareCurrentPackage: `Instead of declaring a module with \`declare module "{{ text }}"\`, ` +
+        `write its contents in directly in {{ preferred }}.`,
+    },
+    schema: [],
+  },
+  create(context) {
+    if (!context.getFilename().endsWith(".d.ts")) {
+      return {}
+    }
+    const parserServices = ESLintUtils.getParserServices(context);
+    const packageName = getCommonDirectoryName(parserServices.program.getRootFileNames());
+    return {
+      // eslint-disable-next-line @typescript-eslint/naming-convention
+      TSModuleDeclaration(node) {
+        if (node.id.type === AST_NODE_TYPES.Literal
+          && (node.id.value === packageName || node.id.value.startsWith(packageName + "/"))) {
+          const text = node.id.value;
+          const preferred = text === packageName ? '"index.d.ts"' : `"${text}.d.ts" or "${text}/index.d.ts`;
+          context.report({
+            messageId: "noDeclareCurrentPackage",
+            data: { text, preferred },
+            node,
+          });
+        }
+      },
+    };
+  },
+});
+
+export = rule;

packages/dtslint/test/no-declare-current-package.test.ts

@@ -0,0 +1,59 @@
+import { ESLintUtils } from "@typescript-eslint/utils";
+
+import * as noDeclareCurrentPackage from "../src/rules/no-declare-current-package";
+
+const ruleTester = new ESLintUtils.RuleTester({
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaVersion: 2018,
+    tsconfigRootDir: __dirname,
+    project: "./tsconfig.no-declare-current-package.json",
+  }
+});
+
+ruleTester.run("no-declare-current-package", noDeclareCurrentPackage, {
+  invalid: [
+    {
+      filename: "index.d.ts",
+      code: `module "test" { }`,
+      errors: [
+        {
+          line: 1,
+          messageId: "noDeclareCurrentPackage",
+        },
+      ],
+    },
+  ],
+  valid: [
+    {
+      filename: "index.d.ts",
+      code: `module "foo" { }
+module "foo/bar/baz" { }
+`}
+  ],
+});
+// needed because you can only test one non-file.ts file per tsconfig
+// (and tsconfig is required for typed-based rules)
+const ruleTester2 = new ESLintUtils.RuleTester({
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaVersion: 2018,
+    tsconfigRootDir: __dirname,
+    project: "./tsconfig.no-declare-current-package2.json",
+  }
+});
+
+ruleTester2.run("no-declare-current-package", noDeclareCurrentPackage, {
+  invalid: [{
+      filename: "deep/import.d.ts",
+      code: `module "test/deep/import" { }`,
+      errors: [
+        {
+          line: 1,
+          messageId: "noDeclareCurrentPackage",
+        },
+      ],
+    },
+  ],
+  valid: [],
+});

packages/dtslint/test/tsconfig.json

@@ -4,5 +4,7 @@
     "strict": true,
     "target": "esnext"
   },
-  "files": ["file.ts"]
+    "files": [
+        "file.ts"
+    ]
 }

packages/dtslint/test/tsconfig.no-declare-current-package.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "skipLibCheck": true,
+    "strict": true,
+    "target": "esnext"
+  },
+    "files": [
+        "index.d.ts",
+        "deep/import.d.ts"
+    ]
+}

packages/dtslint/test/tsconfig.no-declare-current-package2.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "skipLibCheck": true,
+    "strict": true,
+    "target": "esnext"
+  },
+    "files": [
+        "file.ts",
+        "deep/import.d.ts"
+    ]
+}

packages/utils/src/collections.ts

@@ -148,26 +148,19 @@ export function isArray(value: any): value is readonly {}[] {
 }
 
 /**
- * Maps an array. If the mapped value is an array, it is spread into the result.
+ * Maps an array. The mapped value is spread into the result.
  *
  * @param array The array to map.
  * @param mapfn The callback used to map the result into one or more values.
  */
 export function flatMap<T, U>(
   array: readonly T[] | undefined,
-  mapfn: (x: T, i: number) => U | readonly U[] | undefined
+  mapfn: (x: T, i: number) => readonly U[]
 ): readonly U[] {
   let result: U[] | undefined;
   if (array) {
     for (let i = 0; i < array.length; i++) {
-      const v = mapfn(array[i], i);
-      if (v) {
-        if (isArray(v)) {
-          result = addRange(result, v);
-        } else {
-          result = append(result, v);
-        }
-      }
+      result = addRange(result, mapfn(array[i], i));
     }
   }
   return result || [];