Support “Minimum” in TS version line (#265)

README.md

@@ -109,7 +109,7 @@ Normally packages will be tested using TypeScript 2.0.
 To use a newer version, specify it by including a comment like so:
 
 ```ts
-// TypeScript Version: 2.1
+// Minimum TypeScript Version: 2.1
 ```
 
 For DefinitelyTyped packages, this should go just under the header (on line 5).

src/index.ts

@@ -195,7 +195,7 @@ async function testTypesVersion(
 ): Promise<void> {
     const minVersionFromComment = getTypeScriptVersionFromComment(indexText);
     if (minVersionFromComment !== undefined && inTypesVersionDirectory) {
-        throw new Error(`Already in the \`ts${lowVersion}\` directory, don't need \`// TypeScript Version\`.`);
+        throw new Error(`Already in the \`ts${lowVersion}\` directory, don't need \`// Minimum TypeScript Version\`.`);
     }
     const minVersion = lowVersion
         || minVersionFromComment && TypeScriptVersion.isSupported(minVersionFromComment) && minVersionFromComment
@@ -238,13 +238,12 @@ function assertPathIsNotBanned(dirPath: string) {
 }
 
 function getTypeScriptVersionFromComment(text: string): AllTypeScriptVersion | undefined {
-    const searchString = "// TypeScript Version: ";
-    const x = text.indexOf(searchString);
-    if (x === -1) {
+    const match = text.match(/\/\/ (?:Minimum)? TypeScript Version: /);
+    if (!match) {
         return undefined;
     }
 
-    let line = text.slice(x, text.indexOf("\n", x));
+    let line = text.slice(match.index, text.indexOf("\n", match.index));
     if (line.endsWith("\r")) {
         line = line.slice(0, line.length - 1);
     }

src/rules/dtHeaderRule.ts

@@ -30,6 +30,7 @@ function walk(ctx: Lint.WalkContext<void>): void {
     if (!isMainFile(sourceFile.fileName, /*allowNested*/ true)) {
         lookFor("// Type definitions for", "Header should only be in `index.d.ts` of the root.");
         lookFor("// TypeScript Version", "TypeScript version should be specified under header in `index.d.ts`.");
+        lookFor("// Minimum TypeScript Version", "TypeScript version should be specified under header in `index.d.ts`.");
         return;
     }
 

src/rules/expectRule.ts

@@ -211,7 +211,7 @@ function walk(
             const msg = `Compile error in typescript@${versionName} but not in typescript@${nextHigherVersion}.\n`;
             const explain = nextHigherVersion === "next"
                 ? "TypeScript@next features not yet supported."
-                : `Fix with a comment '// TypeScript Version: ${nextHigherVersion}' just under the header.`;
+                : `Fix with a comment '// Minimum TypeScript Version: ${nextHigherVersion}' just under the header.`;
             return msg + explain;
         }
     }

test/dt-header/correct/types/foo/index.d.ts.lint

@@ -2,3 +2,4 @@
 // Project: https://github.com/bobby-headers/dt-header
 // Definitions by: Jane Doe <https://github.com/janedoe>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// Minimum TypeScript Version: 3.1