1 files changed, 37 insertions, 0 deletions
diff --git a/jstests/libs/log.js b/jstests/libs/log.js
new file mode 100644
index 00000000000..299a9ab8e0c
--- /dev/null
+++ b/jstests/libs/log.js
@@ -0,0 +1,37 @@
+// Yields every logline that contains the specified fields. The regex escape function used here is
+// drawn from the following:
+// https://stackoverflow.com/questions/3561493/is-there-a-regexp-escape-function-in-javascript
+// https://github.com/ljharb/regexp.escape
+function * findMatchingLogLines(logLines, fields, ignoreFields) {
+    ignoreFields = ignoreFields || [];
+    function escapeRegex(input) {
+        return (typeof input === "string" ? input.replace(/[\^\$\\\.\*\+\?\(\)\[\]\{\}]/g, '\\$&')
+                                          : input);
+    }
+    function lineMatches(line, fields, ignoreFields) {
+        const fieldNames =
+            Object.keys(fields).filter((fieldName) => !ignoreFields.includes(fieldName));
+        return fieldNames.every((fieldName) => {
+            const fieldValue = fields[fieldName];
+            let regex = escapeRegex(fieldName) + ":? ?(" +
+                escapeRegex(checkLog.formatAsLogLine(fieldValue)) + "|" +
+                escapeRegex(checkLog.formatAsLogLine(fieldValue, true)) + ")";
+            const match = line.match(regex);
+            return match && match[0];
+        });
+    }
+
+    for (let line of logLines) {
+        if (lineMatches(line, fields, ignoreFields)) {
+            yield line;
+        }
+    }
+}
+// Finds and returns a logline containing all the specified fields, or null if no such logline
+// was found.
+function findMatchingLogLine(logLines, fields, ignoreFields) {
+    for (let line of findMatchingLogLines(logLines, fields, ignoreFields)) {
+        return line;
+    }
+    return null;
+}