Improve test coverage

internal/collector/collector_test.go

@@ -257,6 +257,70 @@ matched_metric_mem{label_name="label2"} 200
 # TYPE connections gauge
 connections{type="tcp"} 150
 connections{type="udp"} 25
+`,
+		},
+		{
+			name: "value parsing failure",
+			config: &config.Config{
+				Metrics: []config.Metric{
+					{
+						Name:    "parse_fail_metric",
+						Help:    "metric that fails to parse.",
+						Type:    "gauge",
+						Command: "echo 'not_number'",
+					},
+				},
+			},
+			executor: &mockExecutor{
+				output: "not_number",
+			},
+			expectedMetric: ``,
+		},
+		{
+			name: "field index out of range",
+			config: &config.Config{
+				Metrics: []config.Metric{
+					{
+						Name:    "index_metric",
+						Help:    "metric where field index is out of range.",
+						Type:    "gauge",
+						Command: "echo 'one_value'",
+						Field:   1,
+					},
+				},
+			},
+			executor: &mockExecutor{
+				output: "one_value",
+			},
+			expectedMetric: ``,
+		},
+		{
+			name: "sub-metric with no matching pattern",
+			config: &config.Config{
+				Metrics: []config.Metric{
+					{
+						Name:    "filter_metric",
+						Help:    "metric with a sub-metric that filters lines.",
+						Command: "echo -e 'matched_line 100\nunmatched_line 200'",
+						SubMetrics: []config.SubMetric{
+							{
+								Name:  "filtered_sub",
+								Help:  "created for matched lines.",
+								Type:  "gauge",
+								Field: 1,
+								Match: "^matched_line",
+							},
+						},
+					},
+				},
+			},
+			executor: &mockExecutor{
+				output: "matched_line 100\nunmatched_line 200",
+			},
+			expectedMetric: `
+# HELP filter_metric_filtered_sub created for matched lines.
+# TYPE filter_metric_filtered_sub gauge
+filter_metric_filtered_sub 100
 `,
 		},
 	}

internal/config/config.go

@@ -20,10 +20,10 @@ type Logging struct {
 }
 
 type Global struct {
-	Timeout          time.Duration `yaml:"timeout"`
-	CacheTTL         time.Duration `yaml:"cache_ttl"`
-	MaxConcurrent    int           `yaml:"max_concurrent"`
-	CommandBlacklist []string      `yaml:"command_blacklist"`
+	Timeout          time.Duration `yaml:"timeout,omitempty"`
+	CacheTTL         time.Duration `yaml:"cache_ttl,omitempty"`
+	MaxConcurrent    int           `yaml:"max_concurrent,omitempty"`
+	CommandBlacklist []string      `yaml:"command_blacklist,omitempty"`
 }
 
 type Metric struct {

internal/config/parse.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"time"
 
 	"gopkg.in/yaml.v3"
 )
@@ -28,6 +29,18 @@ func GetPath() string {
 	return "configs/config.yaml"
 }
 
+func (c *Config) applyDefaults() {
+	if c.Global.Timeout == 0 {
+		c.Global.Timeout = 30 * time.Second
+	}
+	if c.Global.CacheTTL == 0 {
+		c.Global.CacheTTL = 3 * time.Second
+	}
+	if c.Global.MaxConcurrent == 0 {
+		c.Global.MaxConcurrent = 10
+	}
+}
+
 // Load reads and parses a YAML configuration file into Config struct.
 //
 // Returns an error if the file can`t be read or if the YAML is invalid. Panics if cfg is nil.
@@ -44,6 +57,8 @@ func Load(path string, cfg *Config) error {
 		return fmt.Errorf("failed to parse YAML from file %s: %w", path, err)
 	}
 
+	cfg.applyDefaults()
+
 	err = cfg.Validate()
 	if err != nil {
 		return fmt.Errorf("configuration is invalid: %s", err)