2 files changed, 74 insertions, 9 deletions

diff --git a/jstests/core/apitest_db_profile_level.js b/jstests/core/apitest_db_profile_level.js
index 2172b4ed1cb..20f6ff55df9 100644
--- a/jstests/core/apitest_db_profile_level.js
+++ b/jstests/core/apitest_db_profile_level.js
@@ -1,11 +1,13 @@
 /**
  *  Tests for setting of profile levels
- *  @tags: [does_not_support_stepdowns, requires_profiling]
+ *  @tags: [does_not_support_stepdowns, requires_profiling, requires_fcv_40]
  */
 
 (function() {
     'use strict';
 
+    load("jstests/libs/log.js");  // For findMatchingLogLine, findMatchingLogLines.
+
     /*
      *  be sure the public collection API is complete
      */
@@ -16,25 +18,51 @@
     // other tests that modify profiler level, when run in parallel.
     var profileLevelDB = db.getSiblingDB("apitest_db_profile_level");
 
+    // Checks for the log that was expected to be created when profile level changed.
+    function profilerChangeWasLogged({from, to} = {}) {
+        const globalLog = assert.commandWorked(profileLevelDB.adminCommand({getLog: 'global'}));
+
+        const fieldMatcher = {msg: "Profiler settings changed"};
+        if (from && to) {
+            const lines = [...findMatchingLogLines(globalLog.log, fieldMatcher)];
+            return lines.find(line => line.match(new RegExp(/from:\{ /.source + from.source)) &&
+                                  line.match(new RegExp(/to:\{ /.source + to.source)));
+        } else {
+            return findMatchingLogLine(globalLog.log, fieldMatcher);
+        }
+    }
+
+    profileLevelDB.getProfilingLevel();
+    assert(!profilerChangeWasLogged({from: /level: 0/, to: /level: -1/}),
+           "Didn't expect anything to be logged");
+
+    assert.throws(() => {
+        profileLevelDB.setProfilingLevel(-1);
+    });
+
     profileLevelDB.setProfilingLevel(0);
     assert(profileLevelDB.getProfilingLevel() == 0, "prof level 0");
+    assert(profilerChangeWasLogged({from: /level: 0/, to: /level: 0/}),
+           "Didn't find expected log line");
 
     profileLevelDB.setProfilingLevel(1);
     assert(profileLevelDB.getProfilingLevel() == 1, "p1");
+    assert(profilerChangeWasLogged({from: /level: 0/, to: /level: 1/}),
+           "Didn't find expected log line");
 
     profileLevelDB.setProfilingLevel(2);
     assert(profileLevelDB.getProfilingLevel() == 2, "p2");
+    assert(profilerChangeWasLogged({from: /level: 1/, to: /level: 2/}),
+           "Didn't find expected log line");
 
     profileLevelDB.setProfilingLevel(0);
     assert(profileLevelDB.getProfilingLevel() == 0, "prof level 0");
+    assert(profilerChangeWasLogged({from: /level: 2/, to: /level: 0/}),
+           "Didn't find expected log line");
 
-    var asserted = false;
-    try {
+    assert.throws(() => {
         profileLevelDB.setProfilingLevel(10);
-        assert(false);
-    } catch (e) {
-        asserted = true;
-        assert(e.dbSetProfilingException);
-    }
-    assert(asserted, "should have asserted");
+    });
+    // Check that didn't log an invalid profile level change.
+    assert(!profilerChangeWasLogged({from: /level: 0/, to: /level: 10/}), "Didn't expect log line");
 })();
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;
+}