add testing infra for textDocument/documentSymbol (#987)

* add testing infra for textDocument/documentSymbol

* add failing test for 986

tests/lsp_features/document_symbol.zig

@@ -0,0 +1,83 @@
+const std = @import("std");
+const zls = @import("zls");
+const builtin = @import("builtin");
+
+const tres = @import("tres");
+
+const Context = @import("../context.zig").Context;
+
+const types = zls.types;
+const requests = zls.requests;
+
+const allocator: std.mem.Allocator = std.testing.allocator;
+
+test "documentSymbol - smoke" {
+    try testDocumentSymbol(
+        \\const S = struct {
+        \\    fn f() void {}
+        \\};
+    ,
+        \\Variable S
+        \\  Function f
+    );
+}
+
+// FIXME: https://github.com/zigtools/zls/issues/986
+test "documentSymbol - nested struct with self" {
+    try testDocumentSymbol(
+        \\const Foo = struct {
+        \\    const Self = @This();
+        \\    pub fn foo() !Self {}
+        \\    const Bar = struct {};
+        \\};
+    ,
+        \\Variable Foo
+    );
+}
+
+fn testDocumentSymbol(source: []const u8, want: []const u8) !void {
+    var ctx = try Context.init();
+    defer ctx.deinit();
+
+    const test_uri: []const u8 = switch (builtin.os.tag) {
+        .windows => "file:///C:\\test.zig",
+        else => "file:///test.zig",
+    };
+
+    try ctx.requestDidOpen(test_uri, source);
+
+    const params = types.DocumentSymbolParams{
+        .textDocument = .{ .uri = test_uri },
+    };
+
+    const response = try ctx.requestGetResponse([]types.DocumentSymbol, "textDocument/documentSymbol", params);
+
+    var got = std.ArrayListUnmanaged(u8){};
+    defer got.deinit(allocator);
+
+    var stack: [16][]const types.DocumentSymbol = undefined;
+    var stack_len: usize = 0;
+
+    stack[stack_len] = response.result;
+    stack_len += 1;
+
+    var writer = got.writer(allocator);
+    while (stack_len > 0) {
+        const top = &stack[stack_len - 1];
+        if (top.len > 0) {
+            try std.fmt.format(writer, "{[space]s:[width]}", .{ .space = "", .width = (stack_len - 1) * 2 });
+            try std.fmt.format(writer, "{s} {s}\n", .{ @tagName(top.*[0].kind), top.*[0].name });
+            if (top.*[0].children) |children| {
+                std.debug.assert(stack_len < stack.len);
+                stack[stack_len] = children;
+                stack_len += 1;
+            }
+            top.* = top.*[1..];
+        } else {
+            stack_len -= 1;
+        }
+    }
+    _ = got.pop(); // Final \n
+
+    try std.testing.expectEqualStrings(want, got.items);
+}

tests/tests.zig

@@ -13,6 +13,7 @@ comptime {
     // LSP features
     _ = @import("lsp_features/completion.zig");
     _ = @import("lsp_features/definition.zig");
+    _ = @import("lsp_features/document_symbol.zig");
     _ = @import("lsp_features/folding_range.zig");
     _ = @import("lsp_features/inlay_hints.zig");
     _ = @import("lsp_features/references.zig");