Update migration script and add unit test

app/scripts/migrations/128.test.ts

@@ -0,0 +1,145 @@
+import { migrate, version } from './128';
+
+const oldVersion = 127;
+
+describe(`migration #${version}`, () => {
+  it('updates the version metadata', async () => {
+    const oldStorage = {
+      meta: { version: oldVersion },
+      data: {},
+    };
+
+    const newStorage = await migrate(oldStorage);
+
+    expect(newStorage.meta).toStrictEqual({ version });
+  });
+
+  it('Does nothing if `networkConfigurations` is not in the network controller state', async () => {
+    const oldState = {
+      NetworkController: {
+        selectedNetworkClientId: 'mainnet',
+      },
+    };
+
+    const transformedState = await migrate({
+      meta: { version: oldVersion },
+      data: oldState,
+    });
+
+    expect(transformedState.data).toStrictEqual(oldState);
+  });
+
+  it('Updates MATIC ticker to POL in networkConfigurations', async () => {
+    const oldState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x89': {
+            chainId: '0x89',
+            ticker: 'MATIC',
+          },
+        },
+      },
+    };
+
+    const expectedState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x89': {
+            chainId: '0x89',
+            ticker: 'POL',
+          },
+        },
+      },
+    };
+
+    const transformedState = await migrate({
+      meta: { version: oldVersion },
+      data: oldState,
+    });
+
+    expect(transformedState.data).toStrictEqual(expectedState);
+  });
+
+  it('Does not update tickers for other network configurations', async () => {
+    const oldState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x89': {
+            chainId: '0x89',
+            ticker: 'MATIC',
+          },
+          '0x1': {
+            chainId: '0x1',
+            ticker: 'ETH',
+          },
+        },
+      },
+    };
+
+    const expectedState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x89': {
+            chainId: '0x89',
+            ticker: 'POL',
+          },
+          '0x1': {
+            chainId: '0x1',
+            ticker: 'ETH',
+          },
+        },
+      },
+    };
+
+    const transformedState = await migrate({
+      meta: { version: oldVersion },
+      data: oldState,
+    });
+
+    expect(transformedState.data).toStrictEqual(expectedState);
+  });
+
+  it('Does nothing if the ticker is already POL for the 0x89 chainId', async () => {
+    const oldState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x89': {
+            chainId: '0x89',
+            ticker: 'POL',
+          },
+        },
+      },
+    };
+
+    const transformedState = await migrate({
+      meta: { version: oldVersion },
+      data: oldState,
+    });
+
+    expect(transformedState.data).toStrictEqual(oldState);
+  });
+
+  it('Does nothing if Polygon ChainId (0x89) is not in networkConfigurations', async () => {
+    const oldState = {
+      NetworkController: {
+        networkConfigurations: {
+          '0x1': {
+            chainId: '0x1',
+            ticker: 'ETH',
+          },
+          '0x2a': {
+            chainId: '0x2a',
+            ticker: 'KOVAN',
+          },
+        },
+      },
+    };
+
+    const transformedState = await migrate({
+      meta: { version: oldVersion },
+      data: oldState,
+    });
+
+    expect(transformedState.data).toStrictEqual(oldState);
+  });
+});

app/scripts/migrations/128.ts

@@ -10,7 +10,7 @@ type VersionedData = {
 };
 
 /**
- * Explain the purpose of the migration here.
+ * Migrates MATIC ticker in Network Configuration to POL ticker as per the direction in https://polygon.technology/blog/save-the-date-matic-pol-migration-coming-september-4th-everything-you-need-to-know
  *
  * @param originalVersionedData - Versioned MetaMask extension state, exactly what we persist to dist.
  * @param originalVersionedData.meta - State metadata.
@@ -30,27 +30,26 @@ export async function migrate(
 function transformState(state: Record<string, unknown>) {
   if (
     hasProperty(state, 'NetworkController') &&
-    isObject(state.NetworkController)
+    isObject(state.NetworkController) &&
+    hasProperty(state.NetworkController, 'networkConfigurations') &&
+    isObject(state.NetworkController.networkConfigurations)
   ) {
-    // type NetworkConfiguration and NetworkConfigurationId not exported from NetworkConroller.d.ts
-    // need for reverse lookup. typing to string
-    const existingNetworkConfigsCopy = state.NetworkController
-      .networkConfigurations as Record<
-      string,
-      NetworkConfiguration & {
-        id: string;
+    for (const networkConfiguration of Object.values(
+      state.NetworkController.networkConfigurations as Record<
+        string,
+        {
+          chainId: string;
+          ticker: string;
+        }
+      >,
+    )) {
+      if (
+        networkConfiguration.chainId === '0x89' &&
+        networkConfiguration.ticker === 'MATIC'
+      ) {
+        networkConfiguration.ticker = 'POL';
       }
-    >;
-
-    Object.values(existingNetworkConfigsCopy).forEach((networkConfig) => {
-      if (networkConfig.ticker === 'MATIC') {
-        existingNetworkConfigsCopy[networkConfig.id].ticker = 'POL';
-      }
-    });
-
-    state.NetworkController.networkConfigurations = existingNetworkConfigsCopy;
+    }
   }
-  const newState = state;
-  // transform state here
-  return newState;
+  return state;
 }