feat: implement verifyConditions step

lib/helpers/regexs.js

@@ -5,6 +5,9 @@ export const semVerRegex = new RegExp(
 
 export const regularVersionRegex = composeSemverRegex(/\bversion:\s*"/, /"/);
 export const attributeVersionRegex = composeSemverRegex(/@version\s+"/, /"/);
+export const allVersionRegexs = new RegExp(
+  regularVersionRegex.source + "|" + attributeVersionRegex.source,
+);
 
 function composeSemverRegex(head, tail) {
   return new RegExp(

lib/index.js

@@ -1,9 +1,35 @@
 /* eslint-disable no-unused-vars */
+import SemanticReleaseError from "@semantic-release/error";
+import fs from "node:fs";
+import path from "node:path";
+import { allVersionRegexs } from "./helpers/regexs";
 
 let verified;
 let prepared;
 
-export async function verifyConditions(pluginConfig, context) {
+export async function verifyConditions(_, context) {
+  const { cwd } = context;
+
+  const projectPath = path.resolve(cwd, "mix.exs");
+
+  if (!fs.existsSync(projectPath)) {
+    throw new SemanticReleaseError(
+      "mix.exs not found in the current working directory",
+      "ENOPROJECT",
+    );
+  }
+
+  const projectContent = fs.readFileSync(projectPath, {
+    encoding: "utf-8",
+  });
+
+  if (!projectContent.match(allVersionRegexs)) {
+    throw new SemanticReleaseError(
+      "no version was found in mix.exs",
+      "ENOVERSION",
+    );
+  }
+
   verified = true;
 }