Refactor swift check out of init-action.ts

src/init-action.ts

@@ -56,6 +56,7 @@ import {
   runDatabaseInitCluster,
 } from "./init";
 import { JavaEnvVars, BuiltInLanguage } from "./languages";
+import { isSwiftCompatible } from "./languages/swift";
 import { Logger, withGroupAsync } from "./logging";
 import {
   downloadOverlayBaseDatabaseFromCache,
@@ -418,14 +419,7 @@ async function run(
       logger,
     });
 
-    if (
-      config.languages.includes(BuiltInLanguage.swift) &&
-      process.platform !== "darwin"
-    ) {
-      throw new ConfigurationError(
-        `Swift analysis is only supported on macOS runner images. Please migrate to a macOS runner.`,
-      );
-    }
+    isSwiftCompatible(actionState, config);
 
     if (repositoryPropertiesResult.isFailure()) {
       addNoLanguageDiagnostic(

src/languages/swift.test.ts

@@ -0,0 +1,43 @@
+import test from "ava";
+
+import { createTestConfig, initAllState } from "../testing-utils";
+
+import { isSwiftCompatible } from "./swift";
+
+import { BuiltInLanguage } from ".";
+
+test("isSwiftCompatible doesn't throw for non-Swift languages", (t) => {
+  for (const language of Object.values(BuiltInLanguage)) {
+    if (language === BuiltInLanguage.swift) {
+      continue;
+    }
+
+    t.notThrows(() =>
+      isSwiftCompatible(
+        initAllState(),
+        createTestConfig({ languages: [language] }),
+      ),
+    );
+  }
+});
+
+test("isSwiftCompatible doesn't throw for Swift on darwin", (t) => {
+  t.notThrows(() => {
+    isSwiftCompatible(
+      initAllState({ platform: "darwin" }),
+      createTestConfig({ languages: [BuiltInLanguage.swift] }),
+    );
+  });
+});
+
+const nonDarwinPlatforms: NodeJS.Platform[] = ["linux", "win32"];
+for (const nonDarwinPlatform of nonDarwinPlatforms) {
+  test(`isSwiftCompatible throws for Swift on ${nonDarwinPlatform}`, (t) => {
+    t.throws(() => {
+      isSwiftCompatible(
+        initAllState({ platform: nonDarwinPlatform }),
+        createTestConfig({ languages: [BuiltInLanguage.swift] }),
+      );
+    });
+  });
+}

src/languages/swift.ts

@@ -0,0 +1,28 @@
+import { ActionState } from "../action-common";
+import { Config } from "../config-utils";
+import { ConfigurationError } from "../util";
+
+import { BuiltInLanguage } from ".";
+
+/**
+ * Determines whether we can run a Swift analysis on the current runner.
+ *
+ * @param action The Action state.
+ * @param config The Action configuration.
+ *
+ * @throws {ConfigurationError} If Swift analysis is not possible on the current runner.
+ * @returns True if we can run a Swift analysis.
+ */
+export function isSwiftCompatible(
+  action: ActionState<["Base"]>,
+  config: Config,
+) {
+  if (
+    config.languages.includes(BuiltInLanguage.swift) &&
+    action.platform !== "darwin"
+  ) {
+    throw new ConfigurationError(
+      `Swift analysis is only supported on macOS runner images. Please migrate to a macOS runner.`,
+    );
+  }
+}