Add SolutionBuilderHostBase.getCustomTransformers to be used when emitting. (#44489)

This allows not having to specify the transformers during normal watch scneario
Builds on top of #43984

src/compiler/tsbuildPublic.ts

@@ -85,6 +85,7 @@ namespace ts {
          * writeFileCallback
          */
         writeFile?(path: string, data: string, writeByteOrderMark?: boolean): void;
+        getCustomTransformers?: (project: string) => CustomTransformers | undefined;
 
         getModifiedTime(fileName: string): Date | undefined;
         setModifiedTime(fileName: string, date: Date): void;
@@ -785,7 +786,7 @@ namespace ts {
                 emit: (targetSourceFile, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers) => {
                     if (targetSourceFile || emitOnlyDtsFiles) {
                         return withProgramOrUndefined(
-                            program => program.emit(targetSourceFile, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers)
+                            program => program.emit(targetSourceFile, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers || state.host.getCustomTransformers?.(project))
                         );
                     }
                     executeSteps(BuildStep.SemanticDiagnostics, cancellationToken);
@@ -921,7 +922,7 @@ namespace ts {
                 (name, text, writeByteOrderMark) => outputFiles.push({ name, text, writeByteOrderMark }),
                 cancellationToken,
                 /*emitOnlyDts*/ false,
-                customTransformers
+                customTransformers || state.host.getCustomTransformers?.(project)
             );
             // Don't emit .d.ts if there are decl file errors
             if (declDiagnostics) {
@@ -1060,7 +1061,7 @@ namespace ts {
                     const refName = resolveProjectName(state, ref.path);
                     return parseConfigFile(state, refName, toResolvedConfigFilePath(state, refName));
                 },
-                customTransformers
+                customTransformers || state.host.getCustomTransformers?.(project)
             );
 
             if (isString(outputFiles)) {

src/testRunner/tsconfig.json

@@ -141,6 +141,7 @@
         "unittests/tsbuildWatch/noEmit.ts",
         "unittests/tsbuildWatch/noEmitOnError.ts",
         "unittests/tsbuildWatch/programUpdates.ts",
+        "unittests/tsbuildWatch/publicApi.ts",
         "unittests/tsbuildWatch/reexport.ts",
         "unittests/tsbuildWatch/watchEnvironment.ts",
         "unittests/tsc/composite.ts",

src/testRunner/unittests/tsbuildWatch/publicApi.ts

@@ -0,0 +1,115 @@
+namespace ts.tscWatch {
+    it("unittests:: tsbuildWatch:: watchMode:: Public API with custom transformers", () => {
+        const solution: File = {
+            path: `${projectRoot}/tsconfig.json`,
+            content: JSON.stringify({
+                references: [
+                    { path: "./shared/tsconfig.json" },
+                    { path: "./webpack/tsconfig.json" }
+                ],
+                files: []
+            })
+        };
+        const sharedConfig: File = {
+            path: `${projectRoot}/shared/tsconfig.json`,
+            content: JSON.stringify({
+                compilerOptions: { composite: true },
+            })
+        };
+        const sharedIndex: File = {
+            path: `${projectRoot}/shared/index.ts`,
+            content: `export function f1() { }
+export class c { }
+export enum e { }
+// leading
+export function f2() { } // trailing`
+        };
+        const webpackConfig: File = {
+            path: `${projectRoot}/webpack/tsconfig.json`,
+            content: JSON.stringify({
+                compilerOptions: { composite: true, },
+                references: [{ path: "../shared/tsconfig.json" }]
+            })
+        };
+        const webpackIndex: File = {
+            path: `${projectRoot}/webpack/index.ts`,
+            content: `export function f2() { }
+export class c2 { }
+export enum e2 { }
+// leading
+export function f22() { } // trailing`
+        };
+        const commandLineArgs = ["--b", "--w"];
+        const { sys, baseline, oldSnap } = createBaseline(createWatchedSystem([libFile, solution, sharedConfig, sharedIndex, webpackConfig, webpackIndex], { currentDirectory: projectRoot }));
+        const { cb, getPrograms } = commandLineCallbacks(sys);
+        const buildHost = createSolutionBuilderWithWatchHost(
+            sys,
+            /*createProgram*/ undefined,
+            createDiagnosticReporter(sys, /*pretty*/ true),
+            createBuilderStatusReporter(sys, /*pretty*/ true),
+            createWatchStatusReporter(sys, /*pretty*/ true)
+        );
+        buildHost.afterProgramEmitAndDiagnostics = cb;
+        buildHost.afterEmitBundle = cb;
+        buildHost.getCustomTransformers = getCustomTransformers;
+        const builder = createSolutionBuilderWithWatch(buildHost, [solution.path], { verbose: true });
+        builder.build();
+        runWatchBaseline({
+            scenario: "publicApi",
+            subScenario: "with custom transformers",
+            commandLineArgs,
+            sys,
+            baseline,
+            oldSnap,
+            getPrograms,
+            changes: [
+                {
+                    caption: "change to shared",
+                    change: sys => sys.prependFile(sharedIndex.path, "export function fooBar() {}"),
+                    timeouts: sys => {
+                        sys.checkTimeoutQueueLengthAndRun(1); // Shared
+                        sys.checkTimeoutQueueLengthAndRun(1); // webpack
+                        sys.checkTimeoutQueueLengthAndRun(1); // solution
+                        sys.checkTimeoutQueueLength(0);
+                    }
+                }
+            ],
+            watchOrSolution: builder
+        });
+
+        function getCustomTransformers(project: string): CustomTransformers {
+            const before: TransformerFactory<SourceFile> = context => {
+                return file => visitEachChild(file, visit, context);
+                function visit(node: Node): VisitResult<Node> {
+                    switch (node.kind) {
+                        case SyntaxKind.FunctionDeclaration:
+                            return visitFunction(node as FunctionDeclaration);
+                        default:
+                            return visitEachChild(node, visit, context);
+                    }
+                }
+                function visitFunction(node: FunctionDeclaration) {
+                    addSyntheticLeadingComment(node, SyntaxKind.MultiLineCommentTrivia, `@before${project}`, /*hasTrailingNewLine*/ true);
+                    return node;
+                }
+            };
+
+            const after: TransformerFactory<SourceFile> = context => {
+                return file => visitEachChild(file, visit, context);
+                function visit(node: Node): VisitResult<Node> {
+                    switch (node.kind) {
+                        case SyntaxKind.VariableStatement:
+                            return visitVariableStatement(node as VariableStatement);
+                        default:
+                            return visitEachChild(node, visit, context);
+                    }
+                }
+                function visitVariableStatement(node: VariableStatement) {
+                    addSyntheticLeadingComment(node, SyntaxKind.SingleLineCommentTrivia, `@after${project}`);
+                    return node;
+                }
+            };
+            return { before: [before], after: [after] };
+        }
+    });
+}