From 35d683efa3426de32cf6b87f40165b0866053719 Mon Sep 17 00:00:00 2001
From: Josh Goldberg <me@joshuakgoldberg.com>
Date: Tue, 14 Apr 2020 01:09:52 -0400
Subject: [PATCH] Add merger for @typescript-eslint/consistent-type-assertions;

---
 src/rules/mergers.ts                          |  4 ++-
 .../mergers/consistent-type-assertions.ts     |  5 ++++
 .../tests/consistent-type-assertions.test.ts  | 25 +++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 src/rules/mergers/consistent-type-assertions.ts
 create mode 100644 src/rules/mergers/tests/consistent-type-assertions.test.ts

diff --git a/src/rules/mergers.ts b/src/rules/mergers.ts
index 3697234f4..a1bd04620 100644
--- a/src/rules/mergers.ts
+++ b/src/rules/mergers.ts
@@ -1,12 +1,14 @@
 import { mergeBanTypes } from "./mergers/ban-types";
+import { mergeConsistentTypeAssertions } from "./mergers/consistent-type-assertions";
 import { mergeIndent } from "./mergers/indent";
-import { mergeNoMemberDelimiterStyle } from "./mergers/member-delimiter-style";
 import { mergeNoCaller } from "./mergers/no-caller";
 import { mergeNoEval } from "./mergers/no-eval";
+import { mergeNoMemberDelimiterStyle } from "./mergers/member-delimiter-style";
 import { mergeNoUnnecessaryTypeAssertion } from "./mergers/no-unnecessary-type-assertion";
 
 export const mergers = new Map([
     ["@typescript-eslint/ban-types", mergeBanTypes],
+    ["@typescript-eslint/consistent-type-assertions", mergeConsistentTypeAssertions],
     ["@typescript-eslint/indent", mergeIndent],
     ["@typescript-eslint/member-delimiter-style", mergeNoMemberDelimiterStyle],
     ["@typescript-eslint/no-unnecessary-type-assertion", mergeNoUnnecessaryTypeAssertion],
diff --git a/src/rules/mergers/consistent-type-assertions.ts b/src/rules/mergers/consistent-type-assertions.ts
new file mode 100644
index 000000000..24e943df7
--- /dev/null
+++ b/src/rules/mergers/consistent-type-assertions.ts
@@ -0,0 +1,5 @@
+import { RuleMerger } from "../merger";
+
+export const mergeConsistentTypeAssertions: RuleMerger = (existingOptions, newOptions) => {
+    return [existingOptions?.[0] ?? newOptions?.[0]].filter(Boolean);
+};
diff --git a/src/rules/mergers/tests/consistent-type-assertions.test.ts b/src/rules/mergers/tests/consistent-type-assertions.test.ts
new file mode 100644
index 000000000..3a3c090fa
--- /dev/null
+++ b/src/rules/mergers/tests/consistent-type-assertions.test.ts
@@ -0,0 +1,25 @@
+import { mergeConsistentTypeAssertions } from "../consistent-type-assertions";
+
+const option = {
+    assertionStyle: "never",
+};
+
+describe(mergeConsistentTypeAssertions, () => {
+    test("neither options existing", () => {
+        const result = mergeConsistentTypeAssertions(undefined, undefined);
+
+        expect(result).toEqual([]);
+    });
+
+    test("only existing options", () => {
+        const result = mergeConsistentTypeAssertions([option], undefined);
+
+        expect(result).toEqual([option]);
+    });
+
+    test("only new options", () => {
+        const result = mergeConsistentTypeAssertions(undefined, [option]);
+
+        expect(result).toEqual([option]);
+    });
+});