Fix __typename addition for InlineFragments

CHANGELOG.md

@@ -20,7 +20,7 @@
 - `apollo-graphql`
   - <First `apollo-graphql` related entry goes here>
 - `apollo-language-server`
-  - <First `apollo-language-server` related entry goes here>
+  - Fix \_\_typename addition for InlineFragments [#1286](https://github.com/apollographql/apollo-tooling/pull/1286)
 - `apollo-tools`
   - <First `apollo-tools` related entry goes here>
 - `vscode-apollo`

apollo.config.js

@@ -2,7 +2,8 @@ module.exports = {
   client: {
     name: "Apollo CLI",
     service: "engine@master",
-    includes: ["./packages/apollo-language-server/**/*.ts"]
+    includes: ["./packages/apollo-language-server/**/*.ts"],
+    excludes: ["**/*.test.ts", "**/__tests__/*"]
   },
   engine: {
     frontend: "https://engine-staging.apollographql.com",

packages/apollo-language-server/src/utilities/__tests__/graphql.test.ts

@@ -0,0 +1,75 @@
+import gql from "graphql-tag";
+import { print } from "graphql";
+import { withTypenameFieldAddedWhereNeeded } from "../graphql";
+
+describe("withTypenameFieldAddedWhereNeeded", () => {
+  it("properly adds __typename to each selectionSet", () => {
+    const query = gql`
+      query Product {
+        product {
+          sku
+          color {
+            id
+            value
+          }
+        }
+      }
+    `;
+
+    const withTypenames = withTypenameFieldAddedWhereNeeded(query);
+
+    expect(print(withTypenames)).toMatchInlineSnapshot(`
+      "query Product {
+        product {
+          __typename
+          sku
+          color {
+            __typename
+            id
+            value
+          }
+        }
+      }
+      "
+    `);
+  });
+
+  it("adds __typename to InlineFragment nodes (as ApolloClient does)", () => {
+    const query = gql`
+      query CartItems {
+        product {
+          items {
+            ... on Table {
+              material
+            }
+            ... on Paint {
+              color
+            }
+          }
+        }
+      }
+    `;
+
+    const withTypenames = withTypenameFieldAddedWhereNeeded(query);
+
+    expect(print(withTypenames)).toMatchInlineSnapshot(`
+      "query CartItems {
+        product {
+          __typename
+          items {
+            __typename
+            ... on Table {
+              __typename
+              material
+            }
+            ... on Paint {
+              __typename
+              color
+            }
+          }
+        }
+      }
+      "
+    `);
+  });
+});

packages/apollo-language-server/src/utilities/graphql.ts

@@ -136,8 +136,15 @@ export function withTypenameFieldAddedWhereNeeded(ast: ASTNode) {
       }
     },
     leave(node: ASTNode) {
-      if (!(node.kind === "Field" || node.kind === "FragmentDefinition"))
+      if (
+        !(
+          node.kind === "Field" ||
+          node.kind === "FragmentDefinition" ||
+          node.kind === "InlineFragment"
+        )
+      ) {
         return undefined;
+      }
       if (!node.selectionSet) return undefined;
 
       if (true) {