feat: add node API

README.md

@@ -112,8 +112,10 @@ Found 2 dependencies with mismatching versions across the workspace. Fix with `-
 
 ## Options
 
+These options are available on the CLI and as parameters to the [Node API](#node-api).
+
 | Name | Description |
-| --- | --- |
+| :-- | :-- |
 | `--fix` | Whether to autofix inconsistencies (using latest version present). |
 | `--ignore-dep` | Dependency to ignore mismatches for (option can be repeated). |
 | `--ignore-dep-pattern` | RegExp of dependency names to ignore mismatches for (option can be repeated). |
@@ -122,6 +124,18 @@ Found 2 dependencies with mismatching versions across the workspace. Fix with `-
 | `--ignore-path` | Workspace-relative path of packages to ignore mismatches for (option can be repeated). |
 | `--ignore-path-pattern` | RegExp of workspace-relative path of packages to ignore mismatches for (option can be repeated). |
 
+## Node API
+
+| Function | Description |
+| :-- | :-- |
+| `check(path, options)` | Checks for inconsistencies across a workspace. Optionally fixes them. Returns lists of inconsistencies: a complete list, a fixable list, and an un-fixable list. |
+| `mismatchingVersionsToDetailedSummary(versions)` | Returns a string of human-readable tables describing mismatching dependency versions. |
+| `mismatchingVersionsToFixedSummary(versions)` | Returns a string summary of the mismatching dependency versions that were fixed. |
+
+More information about parameters and return values can be found in the types and JSDoc comments.
+
+See an example of how these functions are used in [`lib/cli.ts`](./lib/cli.ts).
+
 ## Related
 
 * [npm-package-json-lint](https://github.com/tclindner/npm-package-json-lint) — use this complementary tool to enforce that your dependency versions use consistent range types (i.e. [prefer-caret-version-dependencies](https://npmpackagejsonlint.org/docs/rules/dependencies/prefer-caret-version-dependencies), [prefer-caret-version-devDependencies](https://npmpackagejsonlint.org/docs/rules/dependencies/prefer-caret-version-devDependencies))

lib/check.ts

@@ -0,0 +1,78 @@
+import {
+  calculateVersionsForEachDependency,
+  calculateMismatchingVersions,
+  filterOutIgnoredDependencies,
+  fixMismatchingVersions,
+} from './dependency-versions.js';
+import { getPackages } from './workspace.js';
+
+/**
+ * Checks for inconsistencies across a workspace. Optionally fixes them.
+ * @param path - path to the workspace root
+ * @param options
+ * @param options.fix - Whether to autofix inconsistencies (using latest version present)
+ * @param options.ignoreDep - Dependency(s) to ignore mismatches for
+ * @param options.ignoreDepPattern - RegExp(s) of dependency names to ignore mismatches for
+ * @param options.ignorePackage - Workspace package(s) to ignore mismatches for
+ * @param options.ignorePackagePattern - RegExp(s) of package names to ignore mismatches for
+ * @param options.ignorePath - Workspace-relative path(s) of packages to ignore mismatches for
+ * @param options.ignorePathPattern - RegExp(s) of workspace-relative path of packages to ignore mismatches for
+ * @returns an object with the following properties:
+ * - `mismatchingVersions`: All the mismatching versions found.
+ * - `mismatchingVersionsFixable`: The mismatching versions that are fixable (these will be fixed in `fix` mode)
+ * - `mismatchingVersionsNotFixable`: The mismatching versions that are not fixable (these will be skipped in `fix` mode).
+ */
+export function check(
+  path: string,
+  options?: {
+    fix?: boolean;
+    ignoreDep?: string[];
+    ignoreDepPattern?: string[];
+    ignorePackage?: string[];
+    ignorePackagePattern?: string[];
+    ignorePath?: string[];
+    ignorePathPattern?: string[];
+  }
+) {
+  const optionsWithDefaults = {
+    fix: false,
+    ignoreDep: [],
+    ignoreDepPattern: [],
+    ignorePackage: [],
+    ignorePackagePattern: [],
+    ignorePath: [],
+    ignorePathPattern: [],
+    ...options,
+  };
+
+  // Calculate.
+  const packages = getPackages(
+    path,
+    optionsWithDefaults.ignorePackage,
+    optionsWithDefaults.ignorePackagePattern.map((s) => new RegExp(s)),
+    optionsWithDefaults.ignorePath,
+    optionsWithDefaults.ignorePathPattern.map((s) => new RegExp(s))
+  );
+
+  const dependencyVersions = calculateVersionsForEachDependency(packages);
+
+  const mismatchingVersions = filterOutIgnoredDependencies(
+    calculateMismatchingVersions(dependencyVersions),
+    optionsWithDefaults.ignoreDep,
+    optionsWithDefaults.ignoreDepPattern.map((s) => new RegExp(s))
+  );
+
+  const resultsAfterFix = fixMismatchingVersions(
+    packages,
+    mismatchingVersions,
+    !optionsWithDefaults.fix // Do dry-run if not fixing.
+  );
+  const mismatchingVersionsFixable = resultsAfterFix.fixable;
+  const mismatchingVersionsNotFixable = resultsAfterFix.notFixable;
+
+  return {
+    mismatchingVersions,
+    mismatchingVersionsFixable,
+    mismatchingVersionsNotFixable,
+  };
+}

lib/cli.ts

@@ -1,20 +1,13 @@
 import { Command, Argument } from 'commander';
 import { readFileSync } from 'node:fs';
-import {
-  calculateVersionsForEachDependency,
-  calculateMismatchingVersions,
-  filterOutIgnoredDependencies,
-  fixMismatchingVersions,
-  MismatchingDependencyVersions,
-} from '../lib/dependency-versions.js';
-import { getPackages } from '../lib/workspace.js';
-import {
-  mismatchingVersionsToOutput,
-  mismatchingVersionsFixedToOutput,
-} from '../lib/output.js';
 import { join, dirname } from 'node:path';
 import type { PackageJson } from 'type-fest';
 import { fileURLToPath } from 'node:url';
+import {
+  mismatchingVersionsToDetailedSummary,
+  mismatchingVersionsToFixedSummary,
+} from './output.js';
+import { check } from './check.js';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 
@@ -81,53 +74,31 @@ export function run() {
       collect,
       []
     )
-    .action(function (
-      path,
-      options: {
-        ignoreDep: string[];
-        ignoreDepPattern: string[];
-        ignorePackage: string[];
-        ignorePackagePattern: string[];
-        ignorePath: string[];
-        ignorePathPattern: string[];
-        fix: boolean;
-      }
-    ) {
-      // Calculate.
-      const packages = getPackages(
-        path,
-        options.ignorePackage,
-        options.ignorePackagePattern.map((s) => new RegExp(s)),
-        options.ignorePath,
-        options.ignorePathPattern.map((s) => new RegExp(s))
-      );
-
-      const dependencyVersions = calculateVersionsForEachDependency(packages);
-
-      let mismatchingVersions = filterOutIgnoredDependencies(
-        calculateMismatchingVersions(dependencyVersions),
-        options.ignoreDep,
-        options.ignoreDepPattern.map((s) => new RegExp(s))
-      );
-      let mismatchingVersionsFixed: MismatchingDependencyVersions = [];
+    .action((path, options) => {
+      const {
+        mismatchingVersions,
+        mismatchingVersionsFixable,
+        mismatchingVersionsNotFixable,
+      } = check(path, options);
 
       if (options.fix) {
-        const resultsAfterFix = fixMismatchingVersions(
-          packages,
-          mismatchingVersions
-        );
-        mismatchingVersions = resultsAfterFix.notFixed;
-        mismatchingVersionsFixed = resultsAfterFix.fixed;
-      }
-
-      // Show output for dependencies we fixed.
-      if (mismatchingVersionsFixed.length > 0) {
-        console.log(mismatchingVersionsFixedToOutput(mismatchingVersionsFixed));
-      }
+        // Show output for dependencies we fixed.
+        if (mismatchingVersionsFixable.length > 0) {
+          console.log(
+            mismatchingVersionsToFixedSummary(mismatchingVersionsFixable)
+          );
+        }
 
-      // Show output for dependencies that still have mismatches.
-      if (mismatchingVersions.length > 0) {
-        console.log(mismatchingVersionsToOutput(mismatchingVersions));
+        // Show output for dependencies that still have mismatches.
+        if (mismatchingVersionsNotFixable.length > 0) {
+          console.log(
+            mismatchingVersionsToDetailedSummary(mismatchingVersionsNotFixable)
+          );
+          process.exitCode = 1;
+        }
+      } else if (mismatchingVersions.length > 0) {
+        // Show output for dependencies that have mismatches.
+        console.log(mismatchingVersionsToDetailedSummary(mismatchingVersions));
         process.exitCode = 1;
       }
     })

lib/dependency-versions.ts

@@ -14,6 +14,7 @@ export type DependenciesToVersionsSeen = Map<
   { package: Package; version: string; isLocalPackageVersion: boolean }[]
 >;
 
+/** A dependency that was found to have mismatching versions, the versions present of it, and the packages each of those versions are seen in. */
 export type MismatchingDependencyVersions = Array<{
   dependency: string;
   versions: {
@@ -287,15 +288,17 @@ function writeDependencyVersion(
   );
 }
 
+// eslint-disable-next-line complexity
 export function fixMismatchingVersions(
   packages: Package[],
-  mismatchingVersions: MismatchingDependencyVersions
+  mismatchingVersions: MismatchingDependencyVersions,
+  dryrun = false
 ): {
-  fixed: MismatchingDependencyVersions;
-  notFixed: MismatchingDependencyVersions;
+  fixable: MismatchingDependencyVersions;
+  notFixable: MismatchingDependencyVersions;
 } {
-  const fixed = [];
-  const notFixed = [];
+  const fixable: MismatchingDependencyVersions = [];
+  const notFixable: MismatchingDependencyVersions = [];
   // Loop through each dependency that has a mismatching versions.
   for (const mismatchingVersion of mismatchingVersions) {
     // Decide what version we should fix to.
@@ -307,7 +310,7 @@ export function fixMismatchingVersions(
       fixedVersion = getIncreasedLatestVersion(versions);
     } catch {
       // Skip this dependency.
-      notFixed.push(mismatchingVersion);
+      notFixable.push(mismatchingVersion);
       continue;
     }
 
@@ -321,7 +324,7 @@ export function fixMismatchingVersions(
       compareVersionRanges(fixedVersion, localPackage.packageJson.version) > 0
     ) {
       // Skip this dependency.
-      notFixed.push(mismatchingVersion);
+      notFixable.push(mismatchingVersion);
       continue;
     }
 
@@ -342,13 +345,15 @@ export function fixMismatchingVersions(
         package_.packageJson.devDependencies[mismatchingVersion.dependency] !==
           fixedVersion
       ) {
-        writeDependencyVersion(
-          package_.pathPackageJson,
-          package_.packageJsonEndsInNewline,
-          'devDependencies',
-          mismatchingVersion.dependency,
-          fixedVersion
-        );
+        if (!dryrun) {
+          writeDependencyVersion(
+            package_.pathPackageJson,
+            package_.packageJsonEndsInNewline,
+            'devDependencies',
+            mismatchingVersion.dependency,
+            fixedVersion
+          );
+        }
         isFixed = true;
       }
 
@@ -358,13 +363,15 @@ export function fixMismatchingVersions(
         package_.packageJson.dependencies[mismatchingVersion.dependency] !==
           fixedVersion
       ) {
-        writeDependencyVersion(
-          package_.pathPackageJson,
-          package_.packageJsonEndsInNewline,
-          'dependencies',
-          mismatchingVersion.dependency,
-          fixedVersion
-        );
+        if (!dryrun) {
+          writeDependencyVersion(
+            package_.pathPackageJson,
+            package_.packageJsonEndsInNewline,
+            'dependencies',
+            mismatchingVersion.dependency,
+            fixedVersion
+          );
+        }
         isFixed = true;
       }
 
@@ -374,24 +381,26 @@ export function fixMismatchingVersions(
         package_.packageJson.resolutions[mismatchingVersion.dependency] !==
           fixedVersion
       ) {
-        writeDependencyVersion(
-          package_.pathPackageJson,
-          package_.packageJsonEndsInNewline,
-          'resolutions',
-          mismatchingVersion.dependency,
-          fixedVersion
-        );
+        if (!dryrun) {
+          writeDependencyVersion(
+            package_.pathPackageJson,
+            package_.packageJsonEndsInNewline,
+            'resolutions',
+            mismatchingVersion.dependency,
+            fixedVersion
+          );
+        }
         isFixed = true;
       }
     }
 
     if (isFixed) {
-      fixed.push(mismatchingVersion);
+      fixable.push(mismatchingVersion);
     }
   }
 
   return {
-    fixed,
-    notFixed,
+    fixable,
+    notFixable,
   };
 }

lib/index.ts

@@ -0,0 +1,7 @@
+// Public Node API.
+
+export { check } from './check.js';
+export {
+  mismatchingVersionsToDetailedSummary,
+  mismatchingVersionsToFixedSummary,
+} from './output.js';

lib/output.ts

@@ -6,7 +6,10 @@ import {
 } from './semver.js';
 import { table } from 'table';
 
-export function mismatchingVersionsToOutput(
+/**
+ * Returns human-readable tables describing mismatching dependency versions.
+ */
+export function mismatchingVersionsToDetailedSummary(
   mismatchingDependencyVersions: MismatchingDependencyVersions
 ): string {
   if (mismatchingDependencyVersions.length === 0) {
@@ -59,7 +62,10 @@ export function mismatchingVersionsToOutput(
   ].join('\n');
 }
 
-export function mismatchingVersionsFixedToOutput(
+/**
+ * Returns a summary of the mismatching dependency versions that were fixed.
+ */
+export function mismatchingVersionsToFixedSummary(
   mismatchingDependencyVersions: MismatchingDependencyVersions
 ): string {
   if (mismatchingDependencyVersions.length === 0) {