fix bugs

src/go/mongolib/explain/explain_test.go

@@ -109,7 +109,7 @@ func TestExplain(t *testing.T) {
 		for _, v := range versions {
 			// For versions < 3.4 parsing "getmore" is not supported and returns error
 			if ok, _ := Constraint("< 3.4", v); ok {
-				expectError["getmore_"+v] = "Cannot explain cmd: getMore"
+				expectError["getmore_"+v] = "Explain failed due to unknown command: getmore"
 			}
 		}
 

src/go/mongolib/proto/system.profile.go

@@ -224,9 +224,20 @@ func (self ExampleQuery) ExplainCmd() bson.D {
 	case "getmore":
 		if self.OriginatingCommand.Len() > 0 {
 			cmd = self.OriginatingCommand
+			for i := range cmd {
+				// drop $db param as it is not supported in MongoDB 3.0
+				if cmd[i].Name == "$db" {
+					if len(cmd)-1 == i {
+						cmd = cmd[:i]
+					} else {
+						cmd = append(cmd[:i], cmd[i+1:]...)
+					}
+					break
+				}
+			}
 		} else {
 			cmd = BsonD{
-				{Name: "getMore", Value: ""},
+				{Name: "getmore", Value: ""},
 			}
 		}
 	case "command":

src/go/pt-mongodb-query-digest/main_test.go

@@ -413,8 +413,7 @@ func testAllOperationsTemplate(t *testing.T, data Data) {
 		},
 	}
 
-	ndocs := "165"
+	expected := `Profiler is disabled for the "test" database but there are \s*[0-9]+ documents in the system.profile collection.
-	expected := `Profiler is disabled for the "test" database but there are ` + ndocs + ` documents in the system.profile collection.
 Using those documents for the stats
 pt-mongodb-query-digest .+
 Host: ` + data.url + `
@@ -425,7 +424,7 @@ Skipping profiled queries on these collections: \[system\.profile\]
 # Ratio    [0-9\.]+  \(docs scanned/returned\)
 # Attribute            pct     total        min         max        avg         95%        stddev      median
 # ==================   ===   ========    ========    ========    ========    ========     =======    ========
-# Count \(docs\)                   ` + ndocs + `\s
+# Count \(docs\)             (\s*[0-9]+)\s
 # Exec Time ms         (\s*[0-9]+){8}\s
 # Docs Scanned         (\s*[0-9\.]+){8}\s
 # Docs Returned        (\s*[0-9\.]+){8}\s