Add README to npm package

.gitignore

@@ -23,8 +23,7 @@ Cargo.lock
 node_modules
 !/fixtures/modules/node_modules
 
-/npm/*/*
-!/npm/sovra/scripts
-!/npm/sovra/package.json
+/npm/*
+!/npm/sovra
 
 /napi/*.node

README.md

@@ -0,0 +1 @@
+npm/sovra/README.md

npm/sovra/README.md

@@ -0,0 +1,62 @@
+# Sovra
+
+Fast test decider for JavaScript projects, written in Rust on top of Oxc.
+
+## Usage
+
+### `getAffected(testFiles: string[], changedFiles: string[], resolverOptions: OxcResolverOptions)`
+
+Returns a subset of `testFiles` that have `changedFiles` in their import graph. This is useful in order to determine which tests to run in a large repo.
+
+#### Arguments
+
+| Name              | Description                                                                                                                         |
+| ----------------- | ----------------------------------------------------------------------------------------------------------------------------------- |
+| `testFiles`       | List of files to check if they were affected by changes                                                                             |
+| `changedFiles`    | List of changed files                                                                                                               |
+| `resolverOptions` | Configuration on how to resolve imports, see [oxc-resolver](https://github.com/oxc-project/oxc-resolver?tab=readme-ov-file#options) |
+
+#### Example
+
+```ts
+import { getAffected } from "sovra";
+import { execSync } from "node:child_process";
+import { glob } from "glob";
+
+const testFiles = glob.sync("src/**/*.spec.{ts,tsx}");
+const changedFiles = execSync("git diff --name-only main", { encoding: "utf8" })
+  .trim()
+  .split("\n");
+const resolverOptions = {
+  tsconfig: {
+    configFile: "tsconfig.json",
+  },
+};
+
+const affected = getAffected(testFiles, changedFiles, resolverOptions);
+
+if (affected.errors) {
+  console.error(...affected.errors);
+} else {
+  console.log(affected.files);
+}
+```
+
+## Test
+
+```bash
+cargo test
+```
+
+## Limitations
+
+Imports using variables or expressions are not supported as they can only be determined during runtime:
+
+```ts
+requre(process.env.SOME_VAR + ".js"); // ❌
+import(`./file.${platform}.mjs`); // ❌
+```
+
+## License
+
+MIT © Joel Arvidsson 2024