From ce1507237765e621051110dc123d3b65f8440dd1 Mon Sep 17 00:00:00 2001
From: Chenjie Shi <tadelesh.shi@live.cn>
Date: Tue, 21 May 2024 23:24:37 +0800
Subject: [PATCH] [tcgc] add description for created discriminator property
 (#873)

fix: https://github.com/Azure/typespec-azure/issues/872
---
 .chronus/changes/discriminator_doc-2024-4-21-11-13-50.md   | 7 +++++++
 packages/typespec-client-generator-core/src/types.ts       | 1 +
 packages/typespec-client-generator-core/test/types.test.ts | 5 +++++
 3 files changed, 13 insertions(+)
 create mode 100644 .chronus/changes/discriminator_doc-2024-4-21-11-13-50.md

diff --git a/.chronus/changes/discriminator_doc-2024-4-21-11-13-50.md b/.chronus/changes/discriminator_doc-2024-4-21-11-13-50.md
new file mode 100644
index 0000000000..bda2efe7eb
--- /dev/null
+++ b/.chronus/changes/discriminator_doc-2024-4-21-11-13-50.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+---
+
+add description for created discriminator property
\ No newline at end of file
diff --git a/packages/typespec-client-generator-core/src/types.ts b/packages/typespec-client-generator-core/src/types.ts
index ce1cdc9874..34e2bdc55e 100644
--- a/packages/typespec-client-generator-core/src/types.ts
+++ b/packages/typespec-client-generator-core/src/types.ts
@@ -503,6 +503,7 @@ function addDiscriminatorToModelType(
     const name = discriminatorProperty ? discriminatorProperty.name : discriminator.propertyName;
     model.properties.splice(0, 0, {
       kind: "property",
+      description: `Discriminator property for ${model.name}.`,
       optional: false,
       discriminator: true,
       serializedName: discriminatorProperty
diff --git a/packages/typespec-client-generator-core/test/types.test.ts b/packages/typespec-client-generator-core/test/types.test.ts
index 62983aee26..d46864c639 100644
--- a/packages/typespec-client-generator-core/test/types.test.ts
+++ b/packages/typespec-client-generator-core/test/types.test.ts
@@ -2241,6 +2241,7 @@ describe("typespec-client-generator-core: types", () => {
       const kindProperty = fish.properties[0];
       ok(kindProperty);
       strictEqual(kindProperty.name, "kind");
+      strictEqual(kindProperty.description, "Discriminator property for Fish.");
       strictEqual(kindProperty.kind, "property");
       strictEqual(kindProperty.discriminator, true);
       strictEqual(kindProperty.type.kind, "string");
@@ -2252,6 +2253,7 @@ describe("typespec-client-generator-core: types", () => {
       const sharktypeProperty = shark.properties[0];
       ok(sharktypeProperty);
       strictEqual(sharktypeProperty.name, "sharktype");
+      strictEqual(sharktypeProperty.description, "Discriminator property for Shark.");
       strictEqual(sharktypeProperty.kind, "property");
       strictEqual(sharktypeProperty.discriminator, true);
       strictEqual(sharktypeProperty.type.kind, "string");
@@ -2282,6 +2284,7 @@ describe("typespec-client-generator-core: types", () => {
       const kindProperty = fish.properties[0];
       ok(kindProperty);
       strictEqual(kindProperty.name, "kind");
+      strictEqual(kindProperty.description, "Discriminator property for Fish.");
       strictEqual(kindProperty.kind, "property");
       strictEqual(kindProperty.discriminator, true);
       strictEqual(kindProperty.type.kind, "string");
@@ -2313,6 +2316,7 @@ describe("typespec-client-generator-core: types", () => {
       const kindProperty = fish.properties[0];
       ok(kindProperty);
       strictEqual(kindProperty.name, "kind");
+      strictEqual(kindProperty.description, "Discriminator property for Fish.");
       strictEqual(kindProperty.kind, "property");
       strictEqual(kindProperty.discriminator, true);
       strictEqual(kindProperty.type.kind, "string");
@@ -2498,6 +2502,7 @@ describe("typespec-client-generator-core: types", () => {
       const dogKindProperty = dog.properties[0];
       ok(dogKindProperty);
       strictEqual(dogKindProperty.type, dogKind);
+      strictEqual(dogKindProperty.description, "Discriminator property for Dog.");
     });
 
     it("discriminator", async () => {