fix: a save merges this page's tracked token change into the stored list (closes #717)

A save wrote `trackedTokens` whole, so two pages on one network dropped each
other's adds and brought back each other's removals.

A save that keeps the network now merges this page's change into the stored
list by contract address. A save that switches networks is unchanged.

`mergeTrackedTokens()` does that merge, and the two other merges of tracked
tokens now call it. It keeps one record per contract address, this page's for
a token both lists hold, so a token held twice no longer multiplies.

Model: opus-5-5

tests/trackedTokensPerNetwork.test.js

@@ -117,6 +117,17 @@ async function chooseNetwork(boot, networkId) {
     await boot.settle();
 }
 
+// Adds NEW_TOKEN_ADDRESS by contract address on SettingsAddToken, as the user
+// does. Returns the record the add tracks.
+async function addNewToken(boot) {
+    const { lookupTokenInfo } = require("../src/shared/balances");
+    const info = { symbol: "NEW", decimals: 18, name: "New Token" };
+    lookupTokenInfo.mockResolvedValueOnce(info);
+    boot.node("settings-addtoken-address").value = NEW_TOKEN_ADDRESS;
+    await boot.click("btn-settings-addtoken-manual");
+    return { address: NEW_TOKEN_ADDRESS, ...info, balanceNotFetched: true };
+}
+
 // The Settings gear, a switch to Sepolia, and Back.
 async function gearSwitchBack(boot) {
     await boot.click("btn-settings");
@@ -685,6 +696,113 @@ test("a token removed while this page waits to take another page's switch is gon
     expect(stored.networkTrackedTokens.mainnet).toEqual([]);
 });
 
+// Another popup page tracks DAI after this page's last save. This page then
+// adds a token. Its save keeps DAI.
+test("a token another page added stays when this page adds a token", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [MAINNET_TOKEN],
+    });
+
+    const added = await addNewToken(boot);
+
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([
+        MAINNET_TOKEN,
+        added,
+    ]);
+});
+
+// Another popup page tracks a new token after this page's last save. This page
+// then removes DAI, as the `[x]` on a tracked token in Settings does. Its save
+// keeps the new token.
+test("a token another page added stays when this page removes a token", async () => {
+    const boot = await bootPopup(
+        unversionedValidProfile({ trackedTokens: [MAINNET_TOKEN] }),
+    );
+    expect(boot.pageErrors).toEqual([]);
+    const otherPageToken = {
+        address: NEW_TOKEN_ADDRESS,
+        symbol: "NEW",
+        decimals: 18,
+        name: "New Token",
+    };
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [MAINNET_TOKEN, otherPageToken],
+    });
+
+    const { state, saveState } = require("../src/shared/state");
+    state.trackedTokens.splice(0, 1);
+    await saveState();
+
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([
+        otherPageToken,
+    ]);
+});
+
+// Another popup page stops tracking DAI after this page's last save. This page
+// still holds DAI and adds a token. Its save does not store DAI again.
+test("a token another page removed stays removed when this page adds a token", async () => {
+    const boot = await bootOnAddToken("mainnet", {
+        trackedTokens: [MAINNET_TOKEN],
+    });
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [],
+    });
+
+    const added = await addNewToken(boot);
+
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([added]);
+});
+
+// Another popup page tracks DAI and the new token after this page's last save,
+// and its refresh has read the new token's balance. This page adds the new token
+// too, so the two pages hold different records for it. The save stores one
+// record for the new token, this page's, and keeps DAI.
+test("a token both pages added is stored once, with this page's record", async () => {
+    const boot = await bootOnAddToken("mainnet");
+    expect(boot.pageErrors).toEqual([]);
+    boot.storage.write("autistmask", {
+        ...boot.storage.read("autistmask"),
+        trackedTokens: [
+            MAINNET_TOKEN,
+            {
+                address: NEW_TOKEN_ADDRESS,
+                symbol: "NEW",
+                decimals: 18,
+                name: "New Token",
+            },
+        ],
+    });
+
+    const added = await addNewToken(boot);
+
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([
+        MAINNET_TOKEN,
+        added,
+    ]);
+});
+
+// This page and the stored list each hold DAI twice. This page then adds a
+// token. Its save stores DAI once.
+test("a token held twice is stored once when this page adds a token", async () => {
+    const boot = await bootOnAddToken("mainnet", {
+        trackedTokens: [MAINNET_TOKEN, MAINNET_TOKEN],
+    });
+    expect(boot.pageErrors).toEqual([]);
+
+    const added = await addNewToken(boot);
+
+    expect(boot.storage.read("autistmask").trackedTokens).toEqual([
+        MAINNET_TOKEN,
+        added,
+    ]);
+});
+
 describe("Back after a switch from the Settings gear", () => {
     test("SettingsAddToken no longer offers the common tokens", async () => {
         const boot = await bootOnAddToken("mainnet");