| 1 | // Copyright 2018 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | /* |
| 6 | Package expect provides support for interpreting structured comments in Go |
| 7 | source code as test expectations. |
| 8 | |
| 9 | This is primarily intended for writing tests of things that process Go source |
| 10 | files, although it does not directly depend on the testing package. |
| 11 | |
| 12 | Collect notes with the Extract or Parse functions, and use the |
| 13 | MatchBefore function to find matches within the lines the comments were on. |
| 14 | |
| 15 | The interpretation of the notes depends on the application. |
| 16 | For example, the test suite for a static checking tool might |
| 17 | use a @diag note to indicate an expected diagnostic: |
| 18 | |
| 19 | fmt.Printf("%s", 1) //@ diag("%s wants a string, got int") |
| 20 | |
| 21 | By contrast, the test suite for a source code navigation tool |
| 22 | might use notes to indicate the positions of features of |
| 23 | interest, the actions to be performed by the test, |
| 24 | and their expected outcomes: |
| 25 | |
| 26 | var x = 1 //@ x_decl |
| 27 | ... |
| 28 | print(x) //@ definition("x", x_decl) |
| 29 | print(x) //@ typeof("x", "int") |
| 30 | |
| 31 | # Note comment syntax |
| 32 | |
| 33 | Note comments always start with the special marker @, which must be the |
| 34 | very first character after the comment opening pair, so //@ or /*@ with no |
| 35 | spaces. |
| 36 | |
| 37 | This is followed by a comma separated list of notes. |
| 38 | |
| 39 | A note always starts with an identifier, which is optionally followed by an |
| 40 | argument list. The argument list is surrounded with parentheses and contains a |
| 41 | comma-separated list of arguments. |
| 42 | The empty parameter list and the missing parameter list are distinguishable if |
| 43 | needed; they result in a nil or an empty list in the Args parameter respectively. |
| 44 | |
| 45 | Arguments are either identifiers or literals. |
| 46 | The literals supported are the basic value literals, of string, float, integer |
| 47 | true, false or nil. All the literals match the standard go conventions, with |
| 48 | all bases of integers, and both quote and backtick strings. |
| 49 | There is one extra literal type, which is a string literal preceded by the |
| 50 | identifier "re" which is compiled to a regular expression. |
| 51 | */ |
| 52 | package expect |
| 53 | |
| 54 | import ( |
| 55 | "bytes" |
| 56 | "fmt" |
| 57 | "go/token" |
| 58 | "regexp" |
| 59 | ) |
| 60 | |
| 61 | // Note is a parsed note from an expect comment. |
| 62 | // It knows the position of the start of the comment, and the name and |
| 63 | // arguments that make up the note. |
| 64 | type Note struct { |
| 65 | Pos token.Pos // The position at which the note identifier appears |
| 66 | Name string // the name associated with the note |
| 67 | Args []interface{} // the arguments for the note |
| 68 | } |
| 69 | |
| 70 | // ReadFile is the type of a function that can provide file contents for a |
| 71 | // given filename. |
| 72 | // This is used in MatchBefore to look up the content of the file in order to |
| 73 | // find the line to match the pattern against. |
| 74 | type ReadFile func(filename string) ([]byte, error) |
| 75 | |
| 76 | // MatchBefore attempts to match a pattern in the line before the supplied pos. |
| 77 | // It uses the FileSet and the ReadFile to work out the contents of the line |
| 78 | // that end is part of, and then matches the pattern against the content of the |
| 79 | // start of that line up to the supplied position. |
| 80 | // The pattern may be either a simple string, []byte or a *regexp.Regexp. |
| 81 | // MatchBefore returns the range of the line that matched the pattern, and |
| 82 | // invalid positions if there was no match, or an error if the line could not be |
| 83 | // found. |
| 84 | func MatchBefore(fset *token.FileSet, readFile ReadFile, end token.Pos, pattern interface{}) (token.Pos, token.Pos, error) { |
| 85 | f := fset.File(end) |
| 86 | content, err := readFile(f.Name()) |
| 87 | if err != nil { |
| 88 | return token.NoPos, token.NoPos, fmt.Errorf("invalid file: %v", err) |
| 89 | } |
| 90 | position := f.Position(end) |
| 91 | startOffset := f.Offset(f.LineStart(position.Line)) |
| 92 | endOffset := f.Offset(end) |
| 93 | line := content[startOffset:endOffset] |
| 94 | matchStart, matchEnd := -1, -1 |
| 95 | switch pattern := pattern.(type) { |
| 96 | case string: |
| 97 | bytePattern := []byte(pattern) |
| 98 | matchStart = bytes.Index(line, bytePattern) |
| 99 | if matchStart >= 0 { |
| 100 | matchEnd = matchStart + len(bytePattern) |
| 101 | } |
| 102 | case []byte: |
| 103 | matchStart = bytes.Index(line, pattern) |
| 104 | if matchStart >= 0 { |
| 105 | matchEnd = matchStart + len(pattern) |
| 106 | } |
| 107 | case *regexp.Regexp: |
| 108 | match := pattern.FindIndex(line) |
| 109 | if len(match) > 0 { |
| 110 | matchStart = match[0] |
| 111 | matchEnd = match[1] |
| 112 | } |
| 113 | } |
| 114 | if matchStart < 0 { |
| 115 | return token.NoPos, token.NoPos, nil |
| 116 | } |
| 117 | return f.Pos(startOffset + matchStart), f.Pos(startOffset + matchEnd), nil |
| 118 | } |
| 119 | |
| 120 | func lineEnd(f *token.File, line int) token.Pos { |
| 121 | if line >= f.LineCount() { |
| 122 | return token.Pos(f.Base() + f.Size()) |
| 123 | } |
| 124 | return f.LineStart(line + 1) |
| 125 | } |
| 126 |
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