--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mlir/test/mlir-lsp-server/hover.test	Tue Jun 15 19:15:29 2021 +0900
@@ -0,0 +1,109 @@
+// RUN: mlir-lsp-server -lit-test < %s | FileCheck -strict-whitespace %s
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"mlir","capabilities":{},"trace":"off"}}
+// -----
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{
+  "uri":"test:///foo.mlir",
+  "languageId":"mlir",
+  "version":1,
+  "text":"func @foo(%arg: i1) {\n%value = constant true\nbr ^bb2\n^bb2:\nreturn\n}"
+}}}
+// -----
+// Hover on an operation.
+{"jsonrpc":"2.0","id":1,"method":"textDocument/hover","params":{
+  "textDocument":{"uri":"test:///foo.mlir"},
+  "position":{"line":1,"character":12}
+}}
+//      CHECK:  "id": 1,
+// CHECK-NEXT:  "jsonrpc": "2.0",
+// CHECK-NEXT:  "result": {
+// CHECK-NEXT:    "contents": {
+// CHECK-NEXT:      "kind": "markdown",
+// CHECK-NEXT:      "value": "```mlir\n%true = \"std.constant\"() {value = true} : () -> i1\n```\n"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:      "end": {
+// CHECK-NEXT:        "character": 17,
+// CHECK-NEXT:        "line": 1
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "start": {
+// CHECK-NEXT:        "character": 9,
+// CHECK-NEXT:        "line": 1
+// CHECK-NEXT:      }
+// CHECK-NEXT:    }
+// CHECK-NEXT:  }
+// -----
+// Hover on an operation result.
+{"jsonrpc":"2.0","id":1,"method":"textDocument/hover","params":{
+  "textDocument":{"uri":"test:///foo.mlir"},
+  "position":{"line":1,"character":2}
+}}
+//      CHECK:  "id": 1,
+// CHECK-NEXT:  "jsonrpc": "2.0",
+// CHECK-NEXT:  "result": {
+// CHECK-NEXT:    "contents": {
+// CHECK-NEXT:      "kind": "markdown",
+// CHECK-NEXT:      "value": "Operation: \"std.constant\"\n\nResult #0\n\nType: `i1`\n\n"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:      "end": {
+// CHECK-NEXT:        "character": 6,
+// CHECK-NEXT:        "line": 1
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "start": {
+// CHECK-NEXT:        "character": 0,
+// CHECK-NEXT:        "line": 1
+// CHECK-NEXT:      }
+// CHECK-NEXT:    }
+// CHECK-NEXT:  }
+// -----
+// Hover on a Block.
+{"jsonrpc":"2.0","id":1,"method":"textDocument/hover","params":{
+  "textDocument":{"uri":"test:///foo.mlir"},
+  "position":{"line":3,"character":2}
+}}
+//      CHECK:  "id": 1,
+// CHECK-NEXT:  "jsonrpc": "2.0",
+// CHECK-NEXT:  "result": {
+// CHECK-NEXT:    "contents": {
+// CHECK-NEXT:      "kind": "markdown",
+// CHECK-NEXT:      "value": "Operation: \"func\"\n\nBlock #1\n\nPredecessors: <Block #0>\n\n"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:      "end": {
+// CHECK-NEXT:        "character": 4,
+// CHECK-NEXT:        "line": 3
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "start": {
+// CHECK-NEXT:        "character": 0,
+// CHECK-NEXT:        "line": 3
+// CHECK-NEXT:      }
+// CHECK-NEXT:    }
+// CHECK-NEXT:  }
+// -----
+// Hover on a Block argument.
+{"jsonrpc":"2.0","id":1,"method":"textDocument/hover","params":{
+  "textDocument":{"uri":"test:///foo.mlir"},
+  "position":{"line":0,"character":12}
+}}
+//      CHECK:  "id": 1,
+// CHECK-NEXT:  "jsonrpc": "2.0",
+// CHECK-NEXT:  "result": {
+// CHECK-NEXT:    "contents": {
+// CHECK-NEXT:      "kind": "markdown",
+// CHECK-NEXT:      "value": "Operation: \"func\"\n\nBlock: <Block #0>\n\nArgument #0\n\nType: `i1`\n\n"
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "range": {
+// CHECK-NEXT:      "end": {
+// CHECK-NEXT:        "character": 14,
+// CHECK-NEXT:        "line": 0
+// CHECK-NEXT:      },
+// CHECK-NEXT:      "start": {
+// CHECK-NEXT:        "character": 10,
+// CHECK-NEXT:        "line": 0
+// CHECK-NEXT:      }
+// CHECK-NEXT:    }
+// CHECK-NEXT:  }
+// -----
+{"jsonrpc":"2.0","id":3,"method":"shutdown"}
+// -----
+{"jsonrpc":"2.0","method":"exit"}