1 files changed, 120 insertions, 0 deletions
diff --git a/src/mongo/shell/check_log.js b/src/mongo/shell/check_log.js
new file mode 100644
index 00000000000..d49955f5786
--- /dev/null
+++ b/src/mongo/shell/check_log.js
@@ -0,0 +1,120 @@
+/*
+ * Helper functions which connect to a server, and check its logs for particular strings.
+ */
+var checkLog;
+
+(function() {
+    "use strict";
+
+    if (checkLog) {
+        return;  // Protect against this file being double-loaded.
+    }
+
+    checkLog = (function() {
+        var getGlobalLog = function(conn) {
+            var cmdRes;
+            try {
+                cmdRes = conn.adminCommand({getLog: 'global'});
+            } catch (e) {
+                // Retry with network errors.
+                print("checkLog ignoring failure: " + e);
+                return null;
+            }
+
+            return assert.commandWorked(cmdRes).log;
+        };
+
+        /*
+         * Calls the 'getLog' function on the provided connection 'conn' to see if the provided msg
+         * is found in the logs. Note: this function does not throw an exception, so the return
+         * value should not be ignored.
+         */
+        const checkContainsOnce = function(conn, msg) {
+            const logMessages = getGlobalLog(conn);
+            if (logMessages === null) {
+                return false;
+            }
+            for (let logMsg of logMessages) {
+                if (logMsg.includes(msg)) {
+                    return true;
+                }
+            }
+            return false;
+        };
+
+        /*
+         * Calls the 'getLog' function at regular intervals on the provided connection 'conn' until
+         * the provided 'msg' is found in the logs, or it times out. Throws an exception on timeout.
+         */
+        var contains = function(conn, msg, timeout = 5 * 60 * 1000) {
+            assert.soon(function() {
+                return checkContainsOnce(conn, msg);
+            }, 'Could not find log entries containing the following message: ' + msg, timeout, 300);
+        };
+
+        /*
+         * Calls the 'getLog' function at regular intervals on the provided connection 'conn' until
+         * the provided 'msg' is found in the logs exactly 'expectedCount' times, or it times out.
+         * Throws an exception on timeout.
+         */
+        var containsWithCount = function(conn, msg, expectedCount, timeout = 5 * 60 * 1000) {
+            var count = 0;
+            assert.soon(
+                function() {
+                    count = 0;
+                    var logMessages = getGlobalLog(conn);
+                    if (logMessages === null) {
+                        return false;
+                    }
+                    for (var i = 0; i < logMessages.length; i++) {
+                        if (logMessages[i].indexOf(msg) != -1) {
+                            count++;
+                        }
+                    }
+
+                    return expectedCount === count;
+                },
+                'Expected ' + expectedCount + ', but instead saw ' + count +
+                    ' log entries containing the following message: ' + msg,
+                timeout,
+                300);
+        };
+
+        /*
+         * Converts a scalar or object to a string format suitable for matching against log output.
+         * Field names are not quoted, and by default strings which are not within an enclosing
+         * object are not escaped. Similarly, integer values without an enclosing object are
+         * serialized as integers, while those within an object are serialized as floats to one
+         * decimal point. NumberLongs are unwrapped prior to serialization.
+         */
+        const formatAsLogLine = function(value, escapeStrings, toDecimal) {
+            if (typeof value === "string") {
+                return (escapeStrings ? `"${value}"` : value);
+            } else if (typeof value === "number") {
+                return (Number.isInteger(value) && toDecimal ? value.toFixed(1) : value);
+            } else if (value instanceof NumberLong) {
+                return `${value}`.match(/NumberLong..(.*)../m)[1];
+            } else if (typeof value !== "object") {
+                return value;
+            } else if (Object.keys(value).length === 0) {
+                return Array.isArray(value) ? "[]" : "{}";
+            }
+            let serialized = [];
+            escapeStrings = toDecimal = true;
+            for (let fieldName in value) {
+                const valueStr = formatAsLogLine(value[fieldName], escapeStrings, toDecimal);
+                serialized.push(Array.isArray(value) ? valueStr : `${fieldName}: ${valueStr}`);
+            }
+            return (Array.isArray(value) ? `[ ${serialized.join(', ')} ]`
+                                         : `{ ${serialized.join(', ')} }`);
+        };
+
+        return {
+            getGlobalLog: getGlobalLog,
+            checkContainsOnce: checkContainsOnce,
+            contains: contains,
+            containsWithCount: containsWithCount,
+            formatAsLogLine: formatAsLogLine
+        };
+    })();
+})();