marker

Documentation

Overview

Package marker defines a framework for running "marker" tests, each defined by a file in the testdata subdirectory.

Use this command to run the tests:

$ go test ./gopls/internal/test/marker [-update]

A marker test uses the '//@' marker syntax of the x/tools/go/expect package to annotate source code with various information such as locations and arguments of LSP operations to be executed by the test. The syntax following '@' is parsed as a comma-separated list of ordinary Go function calls, for example

//@foo(a, "b", 3),bar(0)

and delegates to a corresponding function to perform LSP-related operations. See the Marker types documentation below for a list of supported markers.

Each call argument is converted to the type of the corresponding parameter of the designated function. The conversion logic may use the surrounding context, such as the position or nearby text. See the Argument conversion section below for the full set of special conversions. As a special case, the blank identifier '_' is treated as the zero value of the parameter type.

The test runner collects test cases by searching the given directory for files with the .txt extension. Each file is interpreted as a txtar archive, which is extracted to a temporary directory. The relative path to the .txt file is used as the subtest name. The preliminary section of the file (before the first archive entry) is a free-form comment.

Special files

There are several types of file within the test archive that are given special treatment by the test runner:

• "skip": the presence of this file causes the test to be skipped, with the file content used as the skip message.

• "flags": this file is treated as a whitespace-separated list of flags that configure the MarkerTest instance. Supported flags: -{min,max}_go=go1.20 sets the {min,max}imum Go version for the test (inclusive) -cgo requires that CGO_ENABLED is set and the cgo tool is available -write_sumfile=a,b,c instructs the test runner to generate go.sum files in these directories before running the test. -skip_goos=a,b,c instructs the test runner to skip the test for the listed GOOS values. -skip_goarch=a,b,c does the same for GOARCH. -ignore_extra_diags suppresses errors for unmatched diagnostics TODO(rfindley): using build constraint expressions for -skip_go{os,arch} would be clearer. -filter_builtins=false disables the filtering of builtins from completion results. -filter_keywords=false disables the filtering of keywords from completion results. -errors_ok=true suppresses errors for Error level log entries. TODO(rfindley): support flag values containing whitespace.

• "settings.json": this file is parsed as JSON, and used as the session configuration (see gopls/doc/settings.md)

• "capabilities.json": this file is parsed as JSON client capabilities, and applied as an overlay over the default editor client capabilities. see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#clientCapabilities for more details.

• "env": this file is parsed as a list of VAR=VALUE fields specifying the editor environment.

• Golden files: Within the archive, file names starting with '@' are treated as "golden" content, and are not written to disk, but instead are made available to test methods expecting an argument of type *Golden, using the identifier following '@'. For example, if the first parameter of Foo were of type *Golden, the test runner would convert the identifier a in the call @foo(a, "b", 3) into a *Golden by collecting golden file data starting with "@a/". As a special case, for tests that only need one golden file, the data contained in the file "@a" is indexed in the *Golden value by the empty string "".

• proxy files: any file starting with proxy/ is treated as a Go proxy file. If present, these files are written to a separate temporary directory and GOPROXY is set to file://<proxy directory>.

Marker types

Markers are of two kinds. A few are "value markers" (e.g. @item), which are processed in a first pass and each computes a value that may be referred to by name later. Most are "action markers", which are processed in a second pass and take some action such as testing an LSP operation; they may refer to values computed by value markers.

The following markers are supported within marker tests:

• acceptcompletion(location, label, golden): specifies that accepting the completion candidate produced at the given location with provided label results in the given golden state.

• codeaction(start, end, kind, golden, ...titles): specifies a code action to request for the given range. To support multi-line ranges, the range is defined to be between start.Start and end.End. The golden directory contains changed file content after the code action is applied. If titles are provided, they are used to filter the matching code action.

  TODO(rfindley): consolidate with codeactionedit, via a @loc2 marker that allows binding multi-line locations.

• codeactionedit(range, kind, golden, ...titles): a shorter form of codeaction. Invokes a code action of the given kind for the given in-line range, and compares the resulting formatted unified *edits* (notably, not the full file content) with the golden directory.

• codeactionerr(start, end, kind, wantError): specifies a codeaction that fails with an error that matches the expectation.

• codelens(location, title): specifies that a codelens is expected at the given location, with given title. Must be used in conjunction with @codelenses.

• codelenses(): specifies that textDocument/codeLens should be run for the current document, with results compared to the @codelens annotations in the current document.

• complete(location, ...items): specifies expected completion results at the given location. Must be used in conjunction with @item.

• diag(location, regexp): specifies an expected diagnostic matching the given regexp at the given location. The test runner requires a 1:1 correspondence between observed diagnostics and diag annotations. The diagnostics source and kind fields are ignored, to reduce fuss.

  The specified location must match the start position of the diagnostic, but end positions are ignored.

  TODO(adonovan): in the older marker framework, the annotation asserted two additional fields (source="compiler", kind="error"). Restore them?

• def(src, dst location): performs a textDocument/definition request at the src location, and check the result points to the dst location.

• documentLink(golden): asserts that textDocument/documentLink returns links as described by the golden file.

• foldingrange(golden): performs a textDocument/foldingRange for the current document, and compare with the golden content, which is the original source annotated with numbered tags delimiting the resulting ranges (e.g. <1 kind="..."> ... </1>).

• format(golden): performs a textDocument/format request for the enclosing file, and compare against the named golden file. If the formatting request succeeds, the golden file must contain the resulting formatted source. If the formatting request fails, the golden file must contain the error message.

• highlight(src location, dsts ...location): makes a textDocument/highlight request at the given src location, which should highlight the provided dst locations.

• hover(src, dst location, sm stringMatcher): performs a textDocument/hover at the src location, and checks that the result is the dst location, with matching hover content.

• hovererr(src, sm stringMatcher): performs a textDocument/hover at the src location, and checks that the error matches the given stringMatcher.

• implementations(src location, want ...location): makes a textDocument/implementation query at the src location and checks that the resulting set of locations matches want.

• incomingcalls(src location, want ...location): makes a callHierarchy/incomingCalls query at the src location, and checks that the set of call.From locations matches want. (These locations are the declarations of the functions enclosing the calls, not the calls themselves.)

• item(label, details, kind): defines a completion item with the provided fields. This information is not positional, and therefore @item markers may occur anywhere in the source. Used in conjunction with @complete, snippet, or rank.

  TODO(rfindley): rethink whether floating @item annotations are the best way to specify completion results.

• loc(name, location): specifies the name for a location in the source. These locations may be referenced by other markers.

• outgoingcalls(src location, want ...location): makes a callHierarchy/outgoingCalls query at the src location, and checks that the set of call.To locations matches want.

• preparerename(src, spn, placeholder): asserts that a textDocument/prepareRename request at the src location expands to the spn location, with given placeholder. If placeholder is "", this is treated as a negative assertion and prepareRename should return nil.

• rename(location, new, golden): specifies a renaming of the identifier at the specified location to the new name. The golden directory contains the transformed files.

• renameerr(location, new, wantError): specifies a renaming that fails with an error that matches the expectation.

• signature(location, label, active): specifies that signatureHelp at the given location should match the provided string, with the active parameter (an index) highlighted.

• suggestedfix(location, regexp, golden): like diag, the location and regexp identify an expected diagnostic. This diagnostic must to have exactly one associated code action of the specified kind. This action is executed for its editing effects on the source files. Like rename, the golden directory contains the expected transformed files.

• suggestedfixerr(location, regexp, kind, wantError): specifies that the suggestedfix operation should fail with an error that matches the expectation. (Failures in the computation to offer a fix do not generally result in LSP errors, so this marker is not appropriate for testing them.)

• rank(location, ...completionItem): executes a textDocument/completion request at the given location, and verifies that each expected completion item occurs in the results, in the expected order. Other unexpected completion items may occur in the results. TODO(rfindley): this exists for compatibility with the old marker tests. Replace this with rankl, and rename. A "!" prefix on a label asserts that the symbol is not a completion candidate.

• rankl(location, ...label): like rank, but only cares about completion item labels.

• refs(location, want ...location): executes a textDocument/references request at the first location and asserts that the result is the set of 'want' locations. The first want location must be the declaration (assumedly unique).

• snippet(location, completionItem, snippet): executes a textDocument/completion request at the location, and searches for a result with label matching that of the provided completion item (TODO(rfindley): accept a label rather than a completion item). Check the result snippet matches the provided snippet.

• symbol(golden): makes a textDocument/documentSymbol request for the enclosing file, formats the response with one symbol per line, sorts it, and compares against the named golden file. Each line is of the form:

  dotted.symbol.name kind "detail" +n lines

  where the "+n lines" part indicates that the declaration spans several lines. The test otherwise makes no attempt to check location information. There is no point to using more than one @symbol marker in a given file.

• token(location, tokenType, mod): makes a textDocument/semanticTokens/range request at the given location, and asserts that the result includes exactly one token with the given token type and modifier string.

• workspacesymbol(query, golden): makes a workspace/symbol request for the given query, formats the response with one symbol per line, and compares against the named golden file. As workspace symbols are by definition a workspace-wide request, the location of the workspace symbol marker does not matter. Each line is of the form:

  location name kind

Argument conversion

Marker arguments are first parsed by the go/expect package, which accepts the following tokens as defined by the Go spec:

• string, int64, float64, and rune literals
• true and false
• nil
• identifiers (type expect.Identifier)
• regular expressions, denoted the two tokens re"abc" (type *regexp.Regexp)

These values are passed as arguments to the corresponding parameter of the test function. Additional value conversions may occur for these argument -> parameter type pairs:

• string->regexp: the argument is parsed as a regular expressions.
• string->location: the argument is converted to the location of the first instance of the argument in the partial line preceding the note.
• regexp->location: the argument is converted to the location of the first match for the argument in the partial line preceding the note. If the regular expression contains exactly one subgroup, the position of the subgroup is used rather than the position of the submatch.
• name->location: the argument is replaced by the named location.
• name->Golden: the argument is used to look up golden content prefixed by @<argument>.
• {string,regexp,identifier}->stringMatcher: a stringMatcher type specifies an expected string, either in the form of a substring that must be present, a regular expression that it must match, or an identifier (e.g. foo) such that the archive entry @foo exists and contains the exact expected string. stringMatchers are used by some markers to match positive results (outputs) and by other markers to match error messages.

Example

Here is a complete example:

This test checks hovering over constants.

-- a.go --
package a

const abc = 0x2a //@hover("b", "abc", abc),hover(" =", "abc", abc)

-- @abc --
```go
const abc untyped int = 42
```

@hover("b", "abc", abc),hover(" =", "abc", abc)

In this example, the @hover annotation tells the test runner to run the hoverMarker function, which has parameters:

(mark marker, src, dsc protocol.Location, g *Golden).

The first argument holds the test context, including fake editor with open files, and sandboxed directory.

Argument converters translate the "b" and "abc" arguments into locations by interpreting each one as a substring (or as a regular expression, if of the form re"a|b") and finding the location of its first occurrence on the preceding portion of the line, and the abc identifier into a the golden content contained in the file @abc. Then the hoverMarker method executes a textDocument/hover LSP request at the src position, and ensures the result spans "abc", with the markdown content from @abc. (Note that the markdown content includes the expect annotation as the doc comment.)

The next hover on the same line asserts the same result, but initiates the hover immediately after "abc" in the source. This tests that we find the preceding identifier when hovering.

Updating golden files

To update golden content in the test archive, it is easier to regenerate content automatically rather than edit it by hand. To do this, run the tests with the -update flag. Only tests that actually run will be updated.

In some cases, golden content will vary by Go version (for example, gopls produces different markdown at Go versions before the 1.19 go/doc update). By convention, the golden content in test archives should match the output at Go tip. Each test function can normalize golden content for older Go versions.

Note that -update does not cause missing @diag or @loc markers to be added.

TODO

• Rename the files .txtar.
• Provide some means by which locations in the standard library (or builtin.go) can be named, so that, for example, we can we can assert that MyError implements the built-in error type.
• If possible, improve handling for optional arguments. Rather than have multiple variations of a marker, it would be nice to support a more flexible signature: can codeaction, codeactionedit, codeactionerr, and suggestedfix be consolidated?