fix(logs): match log filters case-insensitively, message as a substring

cli/logs.go

@@ -14,14 +14,15 @@ var deviceLogsCmd = &cobra.Command{
 	Long: `Streams real-time logs from a device. Press Ctrl+C to stop.
 
 Filters use key=value (include) or key!=value (exclude) syntax.
-Multiple --filter flags are ANDed together.
+Multiple --filter flags are ANDed together. Matching is case-insensitive;
+'message' matches as a substring, every other key matches the whole value.
 
 Supported keys: pid, process, tag, level, subsystem, category, message
 
 Examples:
   mobilecli device logs --filter tag=ActivityManager
   mobilecli device logs --filter process!=SpringBoard
-  mobilecli device logs --filter level=Error --filter process=backboardd`,
+  mobilecli device logs --filter level=error --filter message=timeout`,
 	RunE: func(cmd *cobra.Command, args []string) error {
 		if _, err := commands.ParseLogFilters(logsFilters); err != nil {
 			return err

commands/logs.go

@@ -86,10 +86,22 @@ func getFieldValue(entry devices.LogEntry, key string) string {
 	}
 }
 
+// fieldMatches compares a log field against a filter value. Matching is
+// case-insensitive everywhere so "level=error" matches "Error" (iOS and Android
+// capitalize levels differently), and "message" matches as a substring so a free
+// text filter like "message=timeout" finds the entries that contain it rather
+// than demanding the whole line.
+func fieldMatches(key, fieldValue, filterValue string) bool {
+	if key == "message" {
+		return strings.Contains(strings.ToLower(fieldValue), strings.ToLower(filterValue))
+	}
+	return strings.EqualFold(fieldValue, filterValue)
+}
+
 func matchesFilters(entry devices.LogEntry, filters []LogFilter) bool {
 	for _, f := range filters {
 		fieldValue := getFieldValue(entry, f.Key)
-		match := fieldValue == f.Value
+		match := fieldMatches(f.Key, fieldValue, f.Value)
 		if f.Negate {
 			match = !match
 		}

commands/logs_test.go

@@ -69,6 +69,11 @@ func TestMatchesFiltersRequiresEveryFilterToPass(t *testing.T) {
 		{"one filter of many fails", []string{"level=Error", "tag=Zygote"}, false},
 		{"numeric pid is compared as text", []string{"pid=42"}, true},
 		{"empty field never matches a value", []string{"subsystem=com.apple.UIKit"}, false},
+		{"level is case-insensitive", []string{"level=error"}, true},
+		{"level upper-case still matches", []string{"level=ERROR"}, true},
+		{"case-insensitive exclude fails", []string{"level!=error"}, false},
+		{"process is case-insensitive", []string{"process=springboard"}, true},
+		{"wrong level value still fails", []string{"level=warning"}, false},
 	}
 
 	for _, test := range tests {
@@ -171,3 +176,27 @@ func TestStreamLogsSucceedsWhenEveryEntryIsWritten(t *testing.T) {
 		t.Errorf("expected 3 log lines, got %d", lines)
 	}
 }
+
+func TestMatchesFiltersMessageIsCaseInsensitiveSubstring(t *testing.T) {
+	entry := devices.LogEntry{Message: "Connection timed out after 10s"}
+
+	cases := []struct {
+		filter string
+		want   bool
+	}{
+		{"message=timed out", true},
+		{"message=TIMED OUT", true},
+		{"message=timeout", false},
+		{"message=connection", true},
+		{"message!=timed out", false},
+	}
+	for _, c := range cases {
+		filters, err := ParseLogFilters([]string{c.filter})
+		if err != nil {
+			t.Fatalf("unexpected error for %q: %v", c.filter, err)
+		}
+		if got := matchesFilters(entry, filters); got != c.want {
+			t.Errorf("matchesFilters(%q) = %v, want %v", c.filter, got, c.want)
+		}
+	}
+}