Merge pull request #13 from JakeSidSmith/next-line-assertions

Next line assertions

Author: JakeSidSmith

README.md

@@ -18,7 +18,7 @@ You must be using TypeScript `3.7` or above. This is a peer dependency.
 
 ## The syntax
 
-Simply add a comment with the following structure to the end of any variable declaration:
+Simply add a comment with the following structure to the end of the line, or on the line above:
 
 ```ts
 // @type: ExpectedTypeHere
@@ -30,19 +30,29 @@ Basic examples:
 // Assert variable types
 const myNumber = 1; // @type: number
 
+// @type: number
+const myOtherNumber = 2;
+
 // Assert return type of function
 sendMessage('Hello'); // @type: Promise<string>
 
+// @type: Promise<string>
+sendMessage('Hello again');
+
 // Assert type of class instance
 new MyClass(abc); // @type: MyClass<ABC>
+
+// @type: MyClass<ABC>
+new MyClass(abc);
 ```
 
 Example in tests:
 
 ```ts
 describe('my getter', () => {
   it('should return undefined if any values in the path are nullable', () => {
-    const result = get(obj, ['a', 'b', 'c']); // @type: string | undefined
+    // @type: string | undefined
+    const result = get(obj, ['a', 'b', 'c']);
 
     expect(result).toBe(undefined);
   });

assertions/fail.ts

@@ -31,3 +31,6 @@ class MyClass<T> {
 
 // tslint:disable-next-line:no-unused-expression
 new MyClass(abc); // @type: MyClass<ABC>
+
+// @type: ABC
+removeNull(abc); // @type: ABC

assertions/pass.ts

@@ -31,3 +31,6 @@ class MyClass<T> {
 
 // tslint:disable-next-line:no-unused-expression
 new MyClass(abc); // @type: MyClass<ABC | null>
+
+// @type: ABC
+removeNull(abc);

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@jakesidsmith/tsassert",
-  "version": "0.2.2",
+  "version": "0.2.3",
   "description": "Check TypeScript types against assertion comments",
   "publishConfig": {
     "access": "public"

package.json

@@ -8,7 +8,8 @@ import { indent, isTruthyString } from './utils';
 import { version } from './version';
 
 const MATCHES_GLOB = /(?:}|\)|\*+\/?|\.[t]sx?)$/;
-const MATCHES_TRAILING_COMMENT = /\/\/\s?@type(?::|\s)\s*(.+)\s*?$/;
+const MATCHES_LONELY_COMMENT = /^\s*?\/\/\s?@type(?::|\s)\s*(.+?)\s*?$/;
+const MATCHES_TRAILING_COMMENT = /\/\/\s?@type(?::|\s)\s*(.+?)\s*?$/;
 const MATCHES_NODE_MODULES = /^node_modules/;
 
 const assert = (tree: Tree) => {
@@ -129,15 +130,29 @@ const assert = (tree: Tree) => {
           node.getStart()
         );
         const line = lines[lineIndex];
+        let result = MATCHES_TRAILING_COMMENT.exec(line);
 
-        const result = MATCHES_TRAILING_COMMENT.exec(line);
+        const lineNumber = lineIndex + 1;
+        const fileLine = `${relativeFileName}:${lineNumber}: `;
+
+        if (lineIndex > 0) {
+          const previousLine = lines[lineIndex - 1];
+          const lonelyResult = MATCHES_LONELY_COMMENT.exec(previousLine);
+
+          if (lonelyResult) {
+            if (result) {
+              errors.push(`${fileLine}Found 2 type comments for the same line`);
+              return;
+            } else {
+              result = lonelyResult;
+            }
+          }
+        }
 
         if (result) {
           commentsChecked += 1;
 
           const comment = result[1];
-          const lineNumber = lineIndex + 1;
-          const fileLine = `${relativeFileName}:${lineNumber}: `;
 
           if (ts.isVariableDeclaration(node)) {
             const symbol = checker.getSymbolAtLocation(node.name);