Add alert to show validation errors

extensions/ql-vscode/src/stories/method-modeling/MethodModeling.stories.tsx

@@ -69,3 +69,35 @@ MultipleModelingsModeledMultiple.args = {
   showMultipleModels: true,
   modelingStatus: "saved",
 };
+
+export const MultipleModelingsValidationFailedNeutral = Template.bind({});
+MultipleModelingsValidationFailedNeutral.args = {
+  method,
+  modeledMethods: [
+    createModeledMethod(method),
+    createModeledMethod({
+      ...method,
+      type: "neutral",
+    }),
+  ],
+  showMultipleModels: true,
+  modelingStatus: "unsaved",
+};
+
+export const MultipleModelingsValidationFailedDuplicate = Template.bind({});
+MultipleModelingsValidationFailedDuplicate.args = {
+  method,
+  modeledMethods: [
+    createModeledMethod(method),
+    createModeledMethod({
+      ...method,
+      type: "source",
+      input: "",
+      output: "ReturnValue",
+      kind: "remote",
+    }),
+    createModeledMethod(method),
+  ],
+  showMultipleModels: true,
+  modelingStatus: "unsaved",
+};

extensions/ql-vscode/src/view/common/Alert.tsx

@@ -85,11 +85,28 @@ type Props = {
 
   // Inverse the color scheme
   inverse?: boolean;
+
+  /**
+   * Role is used as the ARIA role. "alert" should only be set if the alert requires
+   * the user's immediate attention. "status" should be set if the alert is not
+   * important enough to require the user's immediate attention.
+   *
+   * Can be left out if the alert is not important enough to require the user's
+   * immediate attention.
+   */
+  role?: "alert" | "status";
 };
 
-export const Alert = ({ type, title, message, actions, inverse }: Props) => {
+export const Alert = ({
+  type,
+  title,
+  message,
+  actions,
+  inverse,
+  role,
+}: Props) => {
   return (
-    <Container type={type} inverse={inverse}>
+    <Container type={type} inverse={inverse} role={role}>
       <Title>
         {getTypeText(type)}: {title}
       </Title>

extensions/ql-vscode/src/view/method-modeling/ModeledMethodAlert.tsx

@@ -0,0 +1,30 @@
+import { ModeledMethodValidationError } from "../../model-editor/shared/validation";
+import TextButton from "../common/TextButton";
+import { Alert } from "../common";
+import * as React from "react";
+import { useCallback } from "react";
+
+type Props = {
+  error: ModeledMethodValidationError;
+  setSelectedIndex: (index: number) => void;
+};
+
+export const ModeledMethodAlert = ({ error, setSelectedIndex }: Props) => {
+  const handleClick = useCallback(() => {
+    setSelectedIndex(error.index);
+  }, [error.index, setSelectedIndex]);
+
+  return (
+    <Alert
+      role="alert"
+      type="error"
+      title={error.title}
+      message={
+        <>
+          {error.message}{" "}
+          <TextButton onClick={handleClick}>{error.actionText}</TextButton>
+        </>
+      }
+    />
+  );
+};

extensions/ql-vscode/src/view/method-modeling/MultipleModeledMethodsPanel.tsx

@@ -1,11 +1,13 @@
 import * as React from "react";
-import { useCallback, useState } from "react";
+import { useCallback, useMemo, useState } from "react";
 import { Method } from "../../model-editor/method";
 import { ModeledMethod } from "../../model-editor/modeled-method";
 import { styled } from "styled-components";
 import { MethodModelingInputs } from "./MethodModelingInputs";
 import { VSCodeButton } from "@vscode/webview-ui-toolkit/react";
 import { Codicon } from "../common";
+import { validateModeledMethods } from "../../model-editor/shared/validation";
+import { ModeledMethodAlert } from "./ModeledMethodAlert";
 
 export type MultipleModeledMethodsPanelProps = {
   method: Method;
@@ -19,9 +21,14 @@ const Container = styled.div`
   gap: 0.25rem;
 
   padding-bottom: 0.5rem;
+  border-top: 0.05rem solid var(--vscode-panelSection-border);
   border-bottom: 0.05rem solid var(--vscode-panelSection-border);
 `;
 
+const AlertContainer = styled.div`
+  margin-top: 0.5rem;
+`;
+
 const Footer = styled.div`
   display: flex;
   flex-direction: row;
@@ -47,8 +54,24 @@ export const MultipleModeledMethodsPanel = ({
     setSelectedIndex((previousIndex) => previousIndex + 1);
   }, []);
 
+  const validationErrors = useMemo(
+    () => validateModeledMethods(modeledMethods),
+    [modeledMethods],
+  );
+
   return (
     <Container>
+      {validationErrors.length > 0 && (
+        <AlertContainer>
+          {validationErrors.map((error, index) => (
+            <ModeledMethodAlert
+              key={index}
+              error={error}
+              setSelectedIndex={setSelectedIndex}
+            />
+          ))}
+        </AlertContainer>
+      )}
       {modeledMethods.length > 0 ? (
         <MethodModelingInputs
           method={method}

extensions/ql-vscode/src/view/method-modeling/__tests__/MultipleModeledMethodsPanel.spec.tsx

@@ -194,6 +194,16 @@ describe(MultipleModeledMethodsPanel.name, () => {
         }),
       ).toHaveValue("source");
     });
+
+    it("does not show errors", () => {
+      render({
+        method,
+        modeledMethods,
+        onChange,
+      });
+
+      expect(screen.queryByRole("alert")).not.toBeInTheDocument();
+    });
   });
 
   describe("with three modeled methods", () => {
@@ -309,4 +319,56 @@ describe(MultipleModeledMethodsPanel.name, () => {
       ).toHaveValue("remote");
     });
   });
+
+  describe("with duplicate modeled methods", () => {
+    const modeledMethods = [
+      createModeledMethod({
+        ...method,
+      }),
+      createModeledMethod({
+        ...method,
+      }),
+    ];
+
+    it("shows errors", () => {
+      render({
+        method,
+        modeledMethods,
+        onChange,
+      });
+
+      expect(screen.getByRole("alert")).toBeInTheDocument();
+    });
+
+    it("shows the correct error message", async () => {
+      render({
+        method,
+        modeledMethods,
+        onChange,
+      });
+
+      expect(
+        screen.getByText("Error: Duplicated classification"),
+      ).toBeInTheDocument();
+      expect(
+        screen.getByText(
+          "This method has two identical or conflicting classifications.",
+        ),
+      ).toBeInTheDocument();
+
+      expect(screen.getByText("1/2")).toBeInTheDocument();
+
+      const button = screen.getByText(
+        "Modify or remove the duplicated classification.",
+      );
+
+      await userEvent.click(button);
+
+      expect(screen.getByText("2/2")).toBeInTheDocument();
+
+      expect(
+        screen.getByText("Modify or remove the duplicated classification."),
+      ).toBeInTheDocument();
+    });
+  });
 });