[feature](istanbul-lib-instrument): update ignore regex for "legal" comments

packages/istanbul-lib-instrument/src/visitor.js

@@ -5,9 +5,9 @@ const { SourceCoverage } = require('./source-coverage');
 const { SHA, MAGIC_KEY, MAGIC_VALUE } = require('./constants');
 
 // pattern for istanbul to ignore a section
-const COMMENT_RE = /^\s*istanbul\s+ignore\s+(if|else|next)(?=\W|$)/;
+const COMMENT_RE = /^!?\s*istanbul\s+ignore\s+(if|else|next)(?=\W|$)/;
 // pattern for istanbul to ignore the whole file
-const COMMENT_FILE_RE = /^\s*istanbul\s+ignore\s+(file)(?=\W|$)/;
+const COMMENT_FILE_RE = /^!?\s*istanbul\s+ignore\s+(file)(?=\W|$)/;
 // source map URL pattern
 const SOURCE_MAP_RE = /[#@]\s*sourceMappingURL=(.*)\s*$/m;
 

packages/istanbul-lib-instrument/test/specs/if-hints.yaml

@@ -26,6 +26,20 @@ tests:
     branches: {'0': [1]}
     statements: {'0': 1, '1': 1 }
 
+---
+name: ignore if legal
+code: |
+  output = -1;
+  /*! istanbul ignore if */
+  if (args[0] > args [1])
+     output = args[0];
+tests:
+  - args: [10, 20]
+    out: -1
+    lines: {'1': 1, '3': 1 }
+    branches: {'0': [1]}
+    statements: {'0': 1, '1': 1 }
+
 ---
 name: ignore else with if block
 code: |

packages/istanbul-lib-instrument/test/specs/ignore-legal.yaml

@@ -0,0 +1,9 @@
+---
+name: ignore file legal comment
+code: |
+  /*! istanbul ignore file */
+  output = true === true ? "works" : "doesn't work"
+opts:
+  noCoverage: true
+tests:
+  - name: file is ignored