make makeMinificationVariants take a single base config

Author: lobsterkatie

rollup.config.js

@@ -190,44 +190,39 @@ export function makeBaseBundleConfig(options) {
   return deepMerge(sharedBundleConfig, isAddOn ? addOnBundleConfig : standAloneBundleConfig);
 }
 
-export function makeMinificationVariants(existingConfigs) {
+export function makeMinificationVariants(baseConfig) {
   const newConfigs = [];
 
-  // ensure we've got an array of configs rather than a single config
-  existingConfigs = Array.isArray(existingConfigs) ? existingConfigs : [existingConfigs];
+  const { plugins } = baseConfig;
 
-  existingConfigs.forEach(existingConfig => {
-    const { plugins } = existingConfig;
-
-    // The license plugin has to be last, so it ends up after terser. Otherwise, terser will remove the license banner.
-    assert(
-      getLastElement(plugins).name === 'rollup-plugin-license',
-      `Last plugin in given options should be \`rollup-plugin-license\`. Found ${getLastElement(plugins).name}`,
-    );
+  // The license plugin has to be last, so it ends up after terser. Otherwise, terser will remove the license banner.
+  assert(
+    getLastElement(plugins).name === 'rollup-plugin-license',
+    `Last plugin in given options should be \`rollup-plugin-license\`. Found ${getLastElement(plugins).name}`,
+  );
 
-    const bundleVariants = [
-      {
-        output: {
-          file: `${existingConfig.output.file}.js`,
-        },
-        plugins,
+  const bundleVariants = [
+    {
+      output: {
+        file: `${baseConfig.output.file}.js`,
       },
-      {
-        output: {
-          file: `${existingConfig.output.file}.min.js`,
-        },
-        plugins: insertAt(plugins, -2, terserPlugin),
+      plugins,
+    },
+    {
+      output: {
+        file: `${baseConfig.output.file}.min.js`,
       },
-    ];
-
-    bundleVariants.forEach(variant => {
-      const mergedConfig = deepMerge(existingConfig, variant, {
-        // this makes it so that instead of concatenating the `plugin` properties of the two objects, the first value is
-        // just overwritten by the second value
-        arrayMerge: (first, second) => second,
-      });
-      newConfigs.push(mergedConfig);
+      plugins: insertAt(plugins, -2, terserPlugin),
+    },
+  ];
+
+  bundleVariants.forEach(variant => {
+    const mergedConfig = deepMerge(baseConfig, variant, {
+      // this makes it so that instead of concatenating the `plugin` properties of the two objects, the first value is
+      // just overwritten by the second value
+      arrayMerge: (first, second) => second,
     });
+    newConfigs.push(mergedConfig);
   });
 
   return newConfigs;