Change config merge behaviour (#189)

* Merge rule configurations from right to left

Similar to rules themselves, the rule configurations are now merged from right to left so that options can be partially owerwritten.

Resolves #188

* Add changeset

* Use strict typing

.changeset/slow-buckets-cough.md

@@ -0,0 +1,6 @@
+---
+'@sketch-hq/sketch-assistant-utils': minor
+---
+
+Change rule config merge behaviour. Instead of overwriting the entire rule config, options are
+overwritten individually.

packages/utils/src/assistant/__tests__/index.ts

@@ -78,6 +78,37 @@ describe('assign', () => {
     `)
   })
 
+  test('rule config is merged right to left', () => {
+    expect(
+      assign(
+        createAssistantDefinition({
+          config: {
+            rules: {
+              foo: { active: true, foo: 1, bar: 'hello world!' },
+            },
+          },
+        }),
+        createAssistantDefinition({
+          config: {
+            rules: {
+              foo: { active: true, bar: 'hello everyone!' },
+            },
+          },
+        }),
+      ).config,
+    ).toMatchInlineSnapshot(`
+      Object {
+        "rules": Object {
+          "foo": Object {
+            "active": true,
+            "bar": "hello everyone!",
+            "foo": 1,
+          },
+        },
+      }
+    `)
+  })
+
   test('rules are concatenated', () => {
     expect(
       assign(

packages/utils/src/assistant/index.ts

@@ -4,6 +4,8 @@ import {
   AssistantEnv,
   Maybe,
   RuleDefinition,
+  ReservedRuleOptionNames,
+  RuleConfigGroup,
 } from '@sketch-hq/sketch-assistant-types'
 
 /**
@@ -54,10 +56,19 @@ const assign = (...sources: AssistantDefinition[]): AssistantDefinition => {
         ...(typeof acc.config.defaultSeverity === 'undefined'
           ? {}
           : { defaultSeverity: acc.config.defaultSeverity }),
-        rules: {
-          ...curr.config.rules,
-          ...acc.config.rules,
-        },
+        rules: Object.entries(curr.config.rules).reduceRight((a: RuleConfigGroup, [name, opts]) => {
+          return {
+            ...a,
+            [name]: {
+              ...opts,
+              ...a[name],
+              active:
+                a[name]?.[ReservedRuleOptionNames.active] ??
+                opts?.[ReservedRuleOptionNames.active] ??
+                false,
+            },
+          }
+        }, acc.config.rules),
       },
       rules: [...curr.rules, ...acc.rules],
     }