refactor: consolidate diagnostics funcs into single file (#416)

* refactor: consolidate `diagnostics` funcs into single file

- move `IDiagnostic` and `convertDiagnostic` from `tscache` to `print-diagnostics`, then rename it to `diagnostics.ts`
  - the diagnostic funcs being in `tscache` always felt like a strange place for them
    - especially when `parse-tsconfig` or `print-diagnostics` would import them from `tscache`, which sounded like an unrelated file

- may want to move `diagnostics-format-host` into this file as well, as it is _only_ used in this file
  - leaving as is for now, limiting this change to a smaller one

* test: add unit test for `convertDiagnostic`

- this was previously only covered in integration tests
  - since unit tests don't currently touch `index` or `tscache`, and `convertDiagnostic` was previously in `tscache`
    - another reason why consolidating these functions into one file made sense

* fix(diagnostics): use `formatHost.getNewLine()` instead of `\n`

- since new lines are host OS specific

- this fixes the `convertDiagnostic` test on Windows too, where it was failing

CONTRIBUTING.md

@@ -73,5 +73,5 @@ A useful resource as you dive deeper are the [unit tests](__tests__/). They're g
 1. At this point, you may be ready to read the more complicated bits of [`index`](src/index.ts) in detail and see how it interacts with the other modules.
     - The [integration tests](__tests__/integration/) could be useful to review at this point as well.
 1. Once you're pretty familiar with `index`, you can dive into some of the cache code in [`tscache`](src/tscache.ts) and [`rollingcache`](src/rollingcache.ts).
-1. And finally, you can see some of the Rollup logging nuances in [`context`](src/context.ts) and then the TS logging nuances in [`print-diagnostics`](src/print-diagnostics.ts), and [`diagnostics-format-host`](src/diagnostics-format-host.ts)
+1. And finally, you can see some of the Rollup logging nuances in [`context`](src/context.ts) and then the TS logging nuances in [`diagnostics`](src/diagnostics.ts), and [`diagnostics-format-host`](src/diagnostics-format-host.ts)
     - While these are necessary to the implementation, they are fairly ancillary to understanding and working with the codebase.

__tests__/print-diagnostics.spec.ts → __tests__/diagnostics.spec.ts

@@ -4,19 +4,35 @@ import { red } from "colors/safe";
 
 import { makeContext } from "./fixtures/context";
 import { setTypescriptModule } from "../src/tsproxy";
-import { printDiagnostics } from "../src/print-diagnostics";
+import { formatHost } from "../src/diagnostics-format-host";
+import { convertDiagnostic, printDiagnostics } from "../src/diagnostics";
 
 setTypescriptModule(ts);
 
+const tsDiagnostic = {
+	file: undefined,
+	start: undefined,
+	length: undefined,
+	messageText: "Compiler option 'include' requires a value of type Array.",
+	category: ts.DiagnosticCategory.Error,
+	code: 5024,
+	reportsUnnecessary: undefined,
+	reportsDeprecated: undefined,
+};
+
 const diagnostic = {
 	flatMessage: "Compiler option 'include' requires a value of type Array.",
-	formatted: "\x1B[91merror\x1B[0m\x1B[90m TS5024: \x1B[0mCompiler option 'include' requires a value of type Array.\n",
+	formatted: `\x1B[91merror\x1B[0m\x1B[90m TS5024: \x1B[0mCompiler option 'include' requires a value of type Array.${formatHost.getNewLine()}`,
 	category: ts.DiagnosticCategory.Error,
 	code: 5024,
-	type: 'config'
+	type: "config",
 };
 
-test("print-diagnostics - categories", () => {
+test("convertDiagnostic", () => {
+	expect(convertDiagnostic("config", [tsDiagnostic])).toStrictEqual([diagnostic]);
+});
+
+test("printDiagnostics - categories", () => {
 	const context = makeContext();
 
 	printDiagnostics(context, [diagnostic]);
@@ -38,7 +54,7 @@ test("print-diagnostics - categories", () => {
 	expect(context.debug).toBeCalledTimes(0);
 });
 
-test("print-diagnostics - formatting / style", () => {
+test("printDiagnostics - formatting / style", () => {
 	const context = makeContext();
 	const category = "error"; // string version
 

src/print-diagnostics.ts → src/diagnostics.ts

@@ -1,8 +1,41 @@
+import * as tsTypes from "typescript";
 import { red, white, yellow } from "colors/safe";
 
 import { tsModule } from "./tsproxy";
 import { RollupContext } from "./context";
-import { IDiagnostics } from "./tscache";
+import { formatHost } from "./diagnostics-format-host";
+
+export interface IDiagnostics
+{
+	flatMessage: string;
+	formatted: string;
+	fileLine?: string;
+	category: tsTypes.DiagnosticCategory;
+	code: number;
+	type: string;
+}
+
+export function convertDiagnostic(type: string, data: tsTypes.Diagnostic[]): IDiagnostics[]
+{
+	return data.map((diagnostic) =>
+	{
+		const entry: IDiagnostics = {
+			flatMessage: tsModule.flattenDiagnosticMessageText(diagnostic.messageText, formatHost.getNewLine()),
+			formatted: tsModule.formatDiagnosticsWithColorAndContext(data, formatHost),
+			category: diagnostic.category,
+			code: diagnostic.code,
+			type,
+		};
+
+		if (diagnostic.file && diagnostic.start !== undefined)
+		{
+			const { line, character } = diagnostic.file.getLineAndCharacterOfPosition(diagnostic.start);
+			entry.fileLine = `${diagnostic.file.fileName}(${line + 1},${character + 1})`;
+		}
+
+		return entry;
+	});
+}
 
 export function printDiagnostics(context: RollupContext, diagnostics: IDiagnostics[], pretty = true): void
 {

src/index.ts

@@ -7,11 +7,11 @@ import findCacheDir from "find-cache-dir";
 
 import { RollupContext, VerbosityLevel } from "./context";
 import { LanguageServiceHost } from "./host";
-import { TsCache, convertDiagnostic, convertEmitOutput, getAllReferences, ICode } from "./tscache";
+import { TsCache, convertEmitOutput, getAllReferences, ICode } from "./tscache";
 import { tsModule, setTypescriptModule } from "./tsproxy";
 import { IOptions } from "./ioptions";
 import { parseTsConfig } from "./parse-tsconfig";
-import { printDiagnostics } from "./print-diagnostics";
+import { convertDiagnostic, printDiagnostics } from "./diagnostics";
 import { TSLIB, TSLIB_VIRTUAL, tslibSource, tslibVersion } from "./tslib";
 import { createFilter } from "./get-options-overrides";
 

src/parse-tsconfig.ts

@@ -3,8 +3,7 @@ import * as _ from "lodash";
 
 import { tsModule } from "./tsproxy";
 import { RollupContext } from "./context";
-import { printDiagnostics } from "./print-diagnostics";
-import { convertDiagnostic } from "./tscache";
+import { convertDiagnostic, printDiagnostics } from "./diagnostics";
 import { getOptionsOverrides } from "./get-options-overrides";
 import { IOptions } from "./ioptions";
 

src/tscache.ts

@@ -9,7 +9,7 @@ import { RollupContext } from "./context";
 import { RollingCache } from "./rollingcache";
 import { ICache } from "./icache";
 import { tsModule } from "./tsproxy";
-import { formatHost } from "./diagnostics-format-host";
+import { IDiagnostics, convertDiagnostic } from "./diagnostics";
 
 export interface ICode
 {
@@ -25,16 +25,6 @@ interface INodeLabel
 	dirty: boolean;
 }
 
-export interface IDiagnostics
-{
-	flatMessage: string;
-	formatted: string;
-	fileLine?: string;
-	category: tsTypes.DiagnosticCategory;
-	code: number;
-	type: string;
-}
-
 interface ITypeSnapshot
 {
 	id: string;
@@ -74,29 +64,6 @@ export function getAllReferences(importer: string, snapshot: tsTypes.IScriptSnap
 	}));
 }
 
-export function convertDiagnostic(type: string, data: tsTypes.Diagnostic[]): IDiagnostics[]
-{
-	return data.map((diagnostic) =>
-	{
-		const entry: IDiagnostics =
-			{
-				flatMessage: tsModule.flattenDiagnosticMessageText(diagnostic.messageText, "\n"),
-				formatted: tsModule.formatDiagnosticsWithColorAndContext(data, formatHost),
-				category: diagnostic.category,
-				code: diagnostic.code,
-				type,
-			};
-
-		if (diagnostic.file && diagnostic.start !== undefined)
-		{
-			const { line, character } = diagnostic.file.getLineAndCharacterOfPosition(diagnostic.start);
-			entry.fileLine = `${diagnostic.file.fileName}(${line + 1},${character + 1})`;
-		}
-
-		return entry;
-	});
-}
-
 export class TsCache
 {
 	private cacheVersion = "9";