feat: enforce tagged error messages

script/lint/test.ts

@@ -0,0 +1,121 @@
+import path from "path"
+import { mkdtemp, rm } from "fs/promises"
+
+const cases = [
+  {
+    name: "schema field",
+    errors: 0,
+    source: `import { Schema } from "effect"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", { message: Schema.String }) {}`,
+  },
+  {
+    name: "getter",
+    errors: 0,
+    source: `import { Schema } from "effect"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", {}) {
+  override get message() { return "Example failed" }
+}`,
+  },
+  {
+    name: "initialized property",
+    errors: 0,
+    source: `import { Schema } from "effect"
+const Example = class extends Schema.TaggedErrorClass<Example>()("Example", {}) {
+  override message = "Example failed"
+}`,
+  },
+  {
+    name: "namespace import",
+    errors: 0,
+    source: `import * as Schema from "effect/Schema"
+export namespace Example { export class Error extends Schema.TaggedErrorClass<Error>()("Example", { message: Schema.String }) {} }`,
+  },
+  {
+    name: "spread fields",
+    errors: 0,
+    source: `import { Schema } from "effect"
+const fields = { message: Schema.String }
+class Example extends Schema.TaggedErrorClass<Example>()("Example", { ...fields }) {}`,
+  },
+  {
+    name: "computed fields",
+    errors: 0,
+    source: `import { Schema } from "effect"
+const key = "message"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", { [key]: Schema.String }) {}`,
+  },
+  {
+    name: "unrelated Schema binding",
+    errors: 0,
+    source: `const Schema = getSchema()
+class Example extends Schema.TaggedErrorClass()("Example", {}) {}`,
+  },
+  {
+    name: "missing message",
+    errors: 1,
+    source: `import { Schema } from "effect"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", { cause: Schema.Defect }) {}`,
+  },
+  {
+    name: "static message",
+    errors: 1,
+    source: `import { Schema } from "effect"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", {}) { static message = "Example failed" }`,
+  },
+  {
+    name: "uninitialized property",
+    errors: 1,
+    source: `import { Schema } from "effect"
+class Example extends Schema.TaggedErrorClass<Example>()("Example", {}) { declare message: string }`,
+  },
+  {
+    name: "documented disable",
+    errors: 0,
+    source: `import { Schema } from "effect"
+// oxlint-disable-next-line opencode/tagged-error-message -- internal control-flow sentinel
+class Example extends Schema.TaggedErrorClass<Example>()("Example", {}) {}`,
+  },
+]
+
+const directory = await mkdtemp(path.join(import.meta.dir, "../../.lint-tmp-"))
+const config = path.join(directory, ".oxlintrc.json")
+
+try {
+  await Bun.write(
+    config,
+    JSON.stringify({
+      jsPlugins: [path.join(import.meta.dir, "opencode.mjs")],
+      rules: { "opencode/tagged-error-message": "error" },
+    }),
+  )
+  for (const [index, fixture] of cases.entries()) {
+    const file = path.join(directory, `${index}.ts`)
+    await Bun.write(file, fixture.source)
+    const result = Bun.spawnSync([
+      path.join(import.meta.dir, "../../node_modules/.bin/oxlint"),
+      "--config",
+      config,
+      "--format",
+      "json",
+      file,
+    ])
+    if (!result.stdout.length) throw new Error(`${fixture.name}: ${result.stderr.toString()}`)
+    const diagnostics: unknown = JSON.parse(result.stdout.toString())
+    if (!hasDiagnostics(diagnostics)) throw new Error(`${fixture.name}: invalid Oxlint output`)
+    const errors = diagnostics.diagnostics.filter(
+      (item) => typeof item === "object" && item !== null && "code" in item && item.code === "opencode(tagged-error-message)",
+    ).length
+    if (errors !== fixture.errors)
+      throw new Error(
+        `${fixture.name}: expected ${fixture.errors} errors, received ${errors}\n${result.stdout.toString()}`,
+      )
+  }
+} finally {
+  await rm(directory, { recursive: true, force: true })
+}
+
+console.log(`Validated ${cases.length} tagged error lint fixtures`)
+
+function hasDiagnostics(value: unknown): value is { diagnostics: unknown[] } {
+  return typeof value === "object" && value !== null && "diagnostics" in value && Array.isArray(value.diagnostics)
+}