New framework for testing language server handlers (#1992)

Or the Rego-based ones anyway.. but there's really nothing to stop
us from reusing this elsewhere later. With Regal's language server
moving away from a Go orchestration layer and towards passing through
requests and responses straight to and from OPA wherever possible,
our mostly Go-based tests of routing/handlers increasingly felt
like a bad fit. But while most of our tests should be in Rego, we still
need a solid suite of tests to target the server one layer above in the
stack. Starting out with the Rego handlers, but again, the format should
be easily reusable should we want that.

Since we need to move above Rego here, and "pure" Go isn't particularly
nice for writing or reading tests dealing with `[]byte` inputs and outputs
without marshalling into native Go types, this framework has test expressed
as **markdown** documents. The rationale for this is mainly that I want
all test data compiled in a single document, not a directory of policy +
input + data + more. This makes it very easy to quickly see that given
policy X and input Y, the response will be Z. I think it works very well
here, but would be happy to hear thoughts from others.

Also:
- MUCH improved completion provider now able to optimize for clients
  (such as VS Code) capable of handling a default range for **all**
  items sent back in the response instead of repeating the same
  rather verbose range over and over. This effectively cuts the
  payload sent to the client in half, and results in much snappier
  completions.
- With that — finally seem to be able to set `isIncomplete` to
  `false` for at least the above mentioned clients, meaning that
  completion suggestions now normally only needs to be fetched once
  rather than at every key press. Another huge win!
- A few other improvements to slim down the size of completion items
  in order to avoid allocations
- Fix issue in hover provider that would provider hover tooltip
  for package keyword despite there being no example docs on that
- Various stability issues fixed as I encountered them while working
  on this.

Signed-off-by: Anders Eknert <anders.eknert@apple.com>

Author: anderseknert

bundle/regal/lsp/codeaction/codeaction.rego

@@ -12,7 +12,9 @@ import data.regal.lsp.client
 
 # METADATA
 # entrypoint: true
-result["response"] := actions
+default result["response"] := null
+
+result["response"] := actions if actions != set()
 
 # METADATA
 # description: A set of all code actions applicable in the current document

bundle/regal/lsp/codelens/codelens.rego

@@ -15,7 +15,7 @@ import data.regal.lsp.util.range
 
 # METADATA
 # entrypoint: true
-default result["response"] := []
+default result["response"] := null
 
 result["response"] := lenses if input.regal.file.parse_errors == []
 

bundle/regal/lsp/codelens/codelens_test.rego

@@ -16,7 +16,6 @@ test_code_lenses_for_module if {
 
 	lenses := codelens.lenses
 		with input.params.textDocument.uri as "file://policy.rego"
-		with input.regal.file.name as "policy.rego"
 		with input.regal.file.lines as split(policy, "\n")
 		with data.server.feature_flags.debug_provider as true
 		with data.client.init_options.enableDebugCodelens as true

bundle/regal/lsp/completion/main.rego

@@ -11,21 +11,45 @@
 # scope: subpackages
 package regal.lsp.completion
 
+import data.regal.lsp.client
+import data.regal.lsp.location
+
 import data.regal.util
 
 # METADATA
 # entrypoint: true
+default result["response"] := null
+
 result["response"] := {
 	"items": items,
 	"isIncomplete": true,
 } if {
 	input.method == "textDocument/completion"
+	not _default_edit_range_supported
+}
+
+# Client supports setting a default edit range for completion items.
+result["response"] := {
+	"items": items,
+	"isIncomplete": false,
+	"itemDefaults": {"editRange": range},
+} if {
+	input.method == "textDocument/completion"
+	_default_edit_range_supported
+
+	line := input.regal.file.lines[input.params.position.line]
+	line != ""
+
+	location.in_rule_body(line)
+
+	ref := location.ref_at(line, input.params.position.character + 1)
+	range := location.word_range(ref, input.params.position)
 }
 
 # METADATA
 # schemas:
 #   - input: {}
-result["response"] := data.regal.lsp.completion.resolvers[input.params.data.resolver].resolve if {
+result["response"] := data.regal.lsp.completion.resolvers[input.params.data].resolve if {
 	input.method == "completionItem/resolve"
 } else := input.params if {
 	# if there was nothing to resolve, return the input as-is
@@ -35,7 +59,7 @@ result["response"] := data.regal.lsp.completion.resolvers[input.params.data.reso
 # METADATA
 # description: main entry point for completion suggestions
 # entrypoint: true
-items contains object.union(completion, {"_regal": {"provider": provider}}) if {
+items contains completion if {
 	# exit early if caret position is inside a comment. We currently don't have any provider
 	# where doing completions inside of a comment makes sense. Behavior is also editor-specific:
 	# - Zed: always on, with no way to disable
@@ -59,3 +83,7 @@ inside_comment if {
 	startswith(comment.location, line)
 	util.to_location_no_text(comment.location).col <= input.params.position.character + 1
 }
+
+_default_edit_range_supported if {
+	"editRange" in client.capabilities.textDocument.completion.completionList.itemDefaults
+}

bundle/regal/lsp/completion/main_test.rego

@@ -5,7 +5,7 @@ import data.regal.lsp.completion
 test_completion_entrypoint if {
 	items := completion.items with completion.providers as {"test": {"items": {{"foo": "bar"}}}}
 
-	items == {{"_regal": {"provider": "test"}, "foo": "bar"}}
+	items == {{"foo": "bar"}}
 }
 
 test_inside_comment if completion.inside_comment

bundle/regal/lsp/completion/providers/builtins/builtins.rego

@@ -2,12 +2,19 @@
 # description: Completion suggestions for built-in functions
 package regal.lsp.completion.providers.builtins
 
+import data.regal.lsp.client
 import data.regal.lsp.completion.kind
 import data.regal.lsp.location
 
 # METADATA
 # description: suggest built-in functions matching typed ref
+# scope: document
+
+# METADATA
+# description: without editRange item defaults (large amount of duplicated data)
 items contains item if {
+	not _default_edit_range_supported
+
 	line := input.regal.file.lines[input.params.position.line]
 
 	line != ""
@@ -20,6 +27,7 @@ items contains item if {
 
 	not builtin.infix # avoid suggesting 'eq', 'plus', etc
 	not builtin.deprecated
+	not startswith(builtin.name, "internal.")
 
 	startswith(builtin.name, ref.text)
 
@@ -28,6 +36,37 @@ items contains item if {
 		"kind": kind.function,
 		"detail": "built-in function",
 		"textEdit": {"range": location.word_range(ref, input.params.position), "newText": builtin.name},
-		"data": {"resolver": "builtins"},
+		"data": "builtins",
+	}
+}
+
+# METADATA
+# description: with editRange item defaults (range defined in main, label used as textEdit.newText))
+items contains item if {
+	_default_edit_range_supported
+
+	line := input.regal.file.lines[input.params.position.line]
+
+	not startswith(line, "default ")
+
+	ref := location.ref_at(line, input.params.position.character + 1)
+
+	some builtin in data.workspace.builtins
+
+	not builtin.infix # avoid suggesting 'eq', 'plus', etc
+	not builtin.deprecated
+	not startswith(builtin.name, "internal.")
+
+	startswith(builtin.name, ref.text)
+
+	item := {
+		"label": builtin.name,
+		"kind": kind.function,
+		"detail": "built-in function",
+		"data": "builtins",
 	}
 }
+
+_default_edit_range_supported if {
+	"editRange" in client.capabilities.textDocument.completion.completionList.itemDefaults
+}

bundle/regal/lsp/completion/providers/builtins/builtins_test.rego

@@ -31,7 +31,7 @@ test_simple_builtin_completion if {
 					"start": {"character": 9, "line": 3},
 				},
 			},
-			"data": {"resolver": "builtins"},
+			"data": "builtins",
 		},
 		{
 			"detail": "built-in function",
@@ -44,7 +44,7 @@ test_simple_builtin_completion if {
 					"start": {"character": 9, "line": 3},
 				},
 			},
-			"data": {"resolver": "builtins"},
+			"data": "builtins",
 		},
 	}
 }
@@ -77,7 +77,7 @@ test_simple_builtin_completion_single_match if {
 				"start": {"character": 9, "line": 3},
 			},
 		},
-		"data": {"resolver": "builtins"},
+		"data": "builtins",
 	}}
 }
 
@@ -109,7 +109,7 @@ test_simple_builtin_completion_single_match_longer_ref if {
 				"start": {"character": 9, "line": 3},
 			},
 		},
-		"data": {"resolver": "builtins"},
+		"data": "builtins",
 	}}
 }
 

bundle/regal/lsp/completion/providers/input/input.rego

@@ -29,6 +29,6 @@ items contains item if {
 			"range": location.word_range(word, input.params.position),
 			"newText": "input",
 		},
-		"data": {"resolver": "input"},
+		"data": "input",
 	}
 }

bundle/regal/lsp/completion/providers/input/input_test.rego

@@ -13,7 +13,7 @@ allow if {
 
 	items == {{
 		"detail": "input document",
-		"data": {"resolver": "input"},
+		"data": "input",
 		"kind": 14,
 		"label": "input",
 		"textEdit": {

bundle/regal/lsp/completion/providers/rulerefs/rulerefs.rego

@@ -4,11 +4,10 @@ package regal.lsp.completion.providers.rulerefs
 
 import data.regal.ast
 
+import data.regal.lsp.client
 import data.regal.lsp.completion.kind
 import data.regal.lsp.location
 
-_ref_is_internal(ref) if contains(ref, "._")
-
 _line := input.regal.file.lines[input.params.position.line]
 
 _word := location.ref_at(_line, input.params.position.character + 1)
@@ -37,7 +36,7 @@ _current_package_refs contains ref if {
 _imported_package_refs contains ref if {
 	some ref in _workspace_rule_refs
 
-	not _ref_is_internal(ref)
+	not contains(ref, "._")
 
 	strings.any_prefix_match(ref, _current_file_imports)
 }
@@ -48,7 +47,7 @@ _other_package_refs contains ref if {
 	not ref in _imported_package_refs
 	not ref in _current_package_refs
 
-	not _ref_is_internal(ref)
+	not contains(ref, "._")
 }
 
 # from the current package
@@ -92,17 +91,39 @@ _matching_rule_ref_suggestions contains ref if {
 }
 
 # METADATA
-# description: set of completion suggestions for references to rules
+# description: set of completion suggestions for references to rules (no edit range defaults support)
 items contains item if {
+	not _default_edit_range_supported
+
+	range := location.word_range(_word, input.params.position)
+
 	some ref in _matching_rule_ref_suggestions
 
 	item := {
 		"label": ref,
 		"kind": kind.variable,
 		"detail": "reference",
 		"textEdit": {
-			"range": location.word_range(_word, input.params.position),
+			"range": range,
 			"newText": ref,
 		},
 	}
 }
+
+# METADATA
+# description: with editRange item defaults (range defined in main, label used as textEdit.newText))
+items contains item if {
+	_default_edit_range_supported
+
+	some ref in _matching_rule_ref_suggestions
+
+	item := {
+		"label": ref,
+		"kind": kind.variable,
+		"detail": "reference",
+	}
+}
+
+_default_edit_range_supported if {
+	"editRange" in client.capabilities.textDocument.completion.completionList.itemDefaults
+}