From 601bbd35d969167c5b54cb0e8bad2be0a2165705 Mon Sep 17 00:00:00 2001
From: Davi Kawasaki <davishinjik@gmail.com>
Date: Tue, 5 Jan 2021 08:50:34 -0300
Subject: [PATCH] perf: refactor nextPreVersion to reduce cognitive complexity
 (#35)

---
 lib/updateDeps.js           | 70 ++++++++++++++++++++++++-------------
 test/lib/updateDeps.test.js | 30 +++++++++++++++-
 2 files changed, 75 insertions(+), 25 deletions(-)

diff --git a/lib/updateDeps.js b/lib/updateDeps.js
index 025e953..2475d79 100644
--- a/lib/updateDeps.js
+++ b/lib/updateDeps.js
@@ -35,26 +35,36 @@ const getNextPreVersion = (pkg, tags) => {
 	const lastVersion = pkg._lastRelease && pkg._lastRelease.version;
 	const version = `1.0.0-${pkg._preRelease}.1`;
 
+	// Extract tags:
+	// 1. Set filter to extract only package tags
+	// 2. Get tags from a branch considering the filters established
+	// TODO: replace {cwd: '.'} with multiContext.cwd
 	if (pkg.name) tagFilters.push(pkg.name);
 	if (!tags || !tags.length) tags = getTags(pkg._branch, { cwd: "." }, tagFilters);
 
-	if (lastVersion) {
-		const { prerelease } = semver.parse(lastVersion);
-		const lastPreRelTag = prerelease[0] || null;
+	const lastPreRelTag = getPreReleaseTag(lastVersion);
+	const isNewPreRelTag = lastPreRelTag && lastPreRelTag !== pkg._preRelease;
 
-		// If there was a change in the prerelease tag (e.g. dev to rc), start semver from scratch with the new prerelease tag
-		if (lastPreRelTag && lastPreRelTag !== pkg._preRelease) {
-			return version;
-		}
-
-		return _nextPreHighestVersion(tags, lastVersion, pkg._nextType, pkg._preRelease);
-	}
+	return isNewPreRelTag || !lastVersion
+		? `1.0.0-${pkg._preRelease}.1`
+		: _nextPreVersionCases(tags, lastVersion, pkg._nextType, pkg._preRelease);
+};
 
-	return version;
+/**
+ * Parse the prerelease tag from a semver version.
+ *
+ * @param {string} version Semver version in a string format.
+ * @returns {string|null} preReleaseTag Version prerelease tag or null.
+ * @internal
+ */
+const getPreReleaseTag = (version) => {
+	const parsed = semver.parse(version);
+	if (!parsed) return null;
+	return parsed.prerelease[0] || null;
 };
 
 /**
- * Resolve next prerelease highest version from tags or major/minor/patch.
+ * Resolve next prerelease special cases: highest version from tags or major/minor/patch.
  *
  * @param {Array} tags List of all released tags from package.
  * @param {string} lastVersion Last package version released.
@@ -63,21 +73,32 @@ const getNextPreVersion = (pkg, tags) => {
  * @returns {string|undefined} Next pkg version.
  * @internal
  */
-const _nextPreHighestVersion = (tags, lastVersion, pkgNextType, pkgPreRelease) => {
-	if (semver.prerelease(lastVersion)) {
-		const latestVerTags = getLatestVersion(tags, { withPrerelease: true });
-		// Bump the latest version from tags if:
-		// 1. There is a tag list and a latest version result from the list
-		// 2. The last prerelease tag exists and is the same
-		const bumpLatestVerTags = latestVerTags ? semver.inc(latestVerTags, "prerelease", pkgPreRelease) : null;
-		const bumpLastVer = semver.inc(lastVersion, "prerelease", pkgPreRelease);
-
-		return bumpLatestVerTags ? getHighestVersion(bumpLastVer, bumpLatestVerTags) : bumpLastVer;
-	} else {
+const _nextPreVersionCases = (tags, lastVersion, pkgNextType, pkgPreRelease) => {
+	// Case 1: Normal release on last version and is now converted to a prerelease
+	if (!semver.prerelease(lastVersion)) {
 		const { major, minor, patch } = semver.parse(lastVersion);
-		// Case when last version was a normal release and now it needs to be a prerelease
 		return `${semver.inc(`${major}.${minor}.${patch}`, pkgNextType || "patch")}-${pkgPreRelease}.1`;
 	}
+
+	// Case 2: Validates version with tags
+	const latestTag = getLatestVersion(tags, { withPrerelease: true });
+	return _nextPreHighestVersion(latestTag, lastVersion, pkgPreRelease);
+};
+
+/**
+ * Resolve next prerelease comparing bumped tags versions with last version.
+ *
+ * @param {string|null} latestTag Last released tag from branch or null if non-existent.
+ * @param {string} lastVersion Last version released.
+ * @param {string} pkgPreRelease Prerelease tag from package to-be-released.
+ * @returns {string} Next pkg version.
+ * @internal
+ */
+const _nextPreHighestVersion = (latestTag, lastVersion, pkgPreRelease) => {
+	const bumpFromTags = latestTag ? semver.inc(latestTag, "prerelease", pkgPreRelease) : null;
+	const bumpFromLast = semver.inc(lastVersion, "prerelease", pkgPreRelease);
+
+	return bumpFromTags ? getHighestVersion(bumpFromLast, bumpFromTags) : bumpFromLast;
 };
 
 /**
@@ -283,6 +304,7 @@ const auditManifestChanges = (actualManifest, path) => {
 module.exports = {
 	getNextVersion,
 	getNextPreVersion,
+	getPreReleaseTag,
 	updateManifestDeps,
 	resolveReleaseType,
 	resolveNextVersion,
diff --git a/test/lib/updateDeps.test.js b/test/lib/updateDeps.test.js
index 4f5cb72..7653ed8 100644
--- a/test/lib/updateDeps.test.js
+++ b/test/lib/updateDeps.test.js
@@ -1,4 +1,10 @@
-const { resolveReleaseType, resolveNextVersion, getNextVersion, getNextPreVersion } = require("../../lib/updateDeps");
+const {
+	resolveReleaseType,
+	resolveNextVersion,
+	getNextVersion,
+	getNextPreVersion,
+	getPreReleaseTag,
+} = require("../../lib/updateDeps");
 
 describe("resolveNextVersion()", () => {
 	// prettier-ignore
@@ -197,3 +203,25 @@ describe("getNextPreVersion()", () => {
 		});
 	});
 });
+
+describe("getPreReleaseTag()", () => {
+	// prettier-ignore
+	const cases = [
+		[undefined, null],
+		[null, null],
+		["1.0.0-rc.0", "rc"],
+		["1.0.0-dev.0", "dev"],
+		["1.0.0-dev.2", "dev"],
+		["1.1.0-beta.0", "beta"],
+		["11.0.0", null],
+		["11.1.0", null],
+		["11.0.1", null],
+	]
+
+	cases.forEach(([version, preReleaseTag]) => {
+		it(`${version} gives ${preReleaseTag}`, () => {
+			// prettier-ignore
+			expect(getPreReleaseTag(version)).toBe(preReleaseTag);
+		});
+	});
+});