"Expression value is unused" should not be reported for last expression in notebook cell

packages/pyright-internal/src/analyzer/checker.ts

@@ -1534,6 +1534,18 @@ export class Checker extends ParseTreeWalker {
             }
         }
 
+        if (
+            reportAsUnused &&
+            this._fileInfo.ipythonMode === IPythonMode.CellDocs &&
+            node.parent?.nodeType === ParseNodeType.StatementList &&
+            node.parent.parent?.nodeType === ParseNodeType.Module &&
+            node.parent.statements[node.parent.statements.length - 1] === node
+        ) {
+            // Exclude an expression at the end of a notebook cell, as that is treated as
+            // the cell's value.
+            reportAsUnused = false;
+        }
+
         if (reportAsUnused) {
             this._evaluator.addDiagnostic(
                 this._fileInfo.diagnosticRuleSet.reportUnusedExpression,

packages/pyright-internal/src/analyzer/sourceFile.ts

@@ -1357,7 +1357,7 @@ export class SourceFile {
     }
 
     test_enableIPythonMode(enable: boolean) {
-        this._ipythonMode = enable ? IPythonMode.ConcatDoc : IPythonMode.None;
+        this._ipythonMode = enable ? IPythonMode.CellDocs : IPythonMode.None;
     }
 
     private _buildFileInfo(

packages/pyright-internal/src/tests/harness/fourslash/testState.ts

@@ -545,7 +545,7 @@ export class TestState {
     }
 
     verifyDiagnostics(map?: { [marker: string]: { category: string; message: string } }): void {
-        this._analyze();
+        this.analyze();
 
         // organize things per file
         const resultPerFile = this._getDiagnosticsPerFile();
@@ -671,7 +671,7 @@ export class TestState {
     ): Promise<any> {
         // make sure we don't use cache built from other tests
         this.workspace.serviceInstance.invalidateAndForceReanalysis();
-        this._analyze();
+        this.analyze();
 
         for (const range of this.getRanges()) {
             const name = this.getMarkerName(range.marker!);
@@ -737,7 +737,7 @@ export class TestState {
     }
 
     async verifyCommand(command: Command, files: { [filePath: string]: string }): Promise<any> {
-        this._analyze();
+        this.analyze();
 
         const commandResult = await this._hostSpecificFeatures.execute(
             new TestLanguageService(this.workspace, this.console, this.fs),
@@ -923,7 +923,7 @@ export class TestState {
         },
         verifyCodeActionCount?: boolean
     ): Promise<any> {
-        this._analyze();
+        this.analyze();
 
         for (const range of this.getRanges()) {
             const name = this.getMarkerName(range.marker!);
@@ -1076,7 +1076,7 @@ export class TestState {
         },
         abbrMap?: { [abbr: string]: AbbreviationInfo }
     ): Promise<void> {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const markerName = this.getMarkerName(marker);
@@ -1246,7 +1246,7 @@ export class TestState {
             };
         }
     ): void {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const fileName = marker.fileName;
@@ -1315,7 +1315,7 @@ export class TestState {
             references: DocumentRange[];
         };
     }) {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const fileName = marker.fileName;
@@ -1365,7 +1365,7 @@ export class TestState {
             references: DocumentHighlight[];
         };
     }) {
-        this._analyze();
+        this.analyze();
 
         for (const name of Object.keys(map)) {
             const marker = this.getMarkerByName(name);
@@ -1397,7 +1397,7 @@ export class TestState {
         },
         filter: DefinitionFilter = DefinitionFilter.All
     ) {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const fileName = marker.fileName;
@@ -1425,7 +1425,7 @@ export class TestState {
             definitions: DocumentRange[];
         };
     }) {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const fileName = marker.fileName;
@@ -1454,7 +1454,7 @@ export class TestState {
             changes: FileEditAction[];
         };
     }) {
-        this._analyze();
+        this.analyze();
 
         for (const marker of this.getMarkers()) {
             const fileName = marker.fileName;
@@ -1798,7 +1798,7 @@ export class TestState {
         return position <= editStart ? position : position < editEnd ? -1 : position + length - +(editEnd - editStart);
     }
 
-    private _analyze() {
+    public analyze() {
         while (this.program.analyze()) {
             // Continue to call analyze until it completes. Since we're not
             // specifying a timeout, it should complete the first time.

packages/pyright-internal/src/tests/ipythonMode.test.ts

@@ -560,3 +560,36 @@ function findCommentByOffset(tokens: TextRangeCollection<Token>, offset: number)
 
     return comment;
 }
+
+test('unused expression at end is not error', async () => {
+    const code = `
+// @filename: test.py
+// @ipythonMode: true
+//// 4[|/*marker*/|]
+    `;
+
+    verifyAnalysisDiagnosticCount(code, 0);
+});
+
+test('unused expression is error if within another statement', async () => {
+    const code = `
+// @filename: test.py
+// @ipythonMode: true
+//// if True:
+////     4[|/*marker*/|]
+    `;
+
+    verifyAnalysisDiagnosticCount(code, 1);
+});
+
+function verifyAnalysisDiagnosticCount(code: string, expectedCount: number) {
+    const state = parseAndGetTestState(code).state;
+
+    state.analyze();
+
+    const range = state.getRangeByMarkerName('marker')!;
+    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const diagnostics = source.getDiagnostics(state.configOptions);
+
+    assert.strictEqual(diagnostics?.length, expectedCount);
+}