From fe6c2cdfeef3320d7863dd59f5f141f33f0f9cbb Mon Sep 17 00:00:00 2001
From: alexandra vargas <alexa1866@gmail.com>
Date: Tue, 13 Jan 2026 17:04:28 +0100
Subject: [PATCH] Create unit tests for parser.go

---
 .../pkg/validator/prometheus/parser_test.go   | 137 ++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 apps/dashvalidator/pkg/validator/prometheus/parser_test.go

diff --git a/apps/dashvalidator/pkg/validator/prometheus/parser_test.go b/apps/dashvalidator/pkg/validator/prometheus/parser_test.go
new file mode 100644
index 00000000000..ff9ed421677
--- /dev/null
+++ b/apps/dashvalidator/pkg/validator/prometheus/parser_test.go
@@ -0,0 +1,137 @@
+package prometheus
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestExtractMetrics(t *testing.T) {
+	parser := NewParser()
+
+	tests := []struct {
+		name          string
+		query         string
+		expected      []string
+		expectError   bool
+		errorContains string
+	}{
+		// Category 1: Basic Extraction (3 tests - covers AST node types)
+		{
+			name:     "simple metric",
+			query:    "up",
+			expected: []string{"up"},
+		},
+		{
+			name:     "metric with labels",
+			query:    `up{job="api"}`,
+			expected: []string{"up"},
+		},
+		{
+			name:     "range selector",
+			query:    "up[5m]",
+			expected: []string{"up"},
+		},
+
+		// Category 2: Function Composition (2 tests - nested complexity)
+		{
+			name:     "single function",
+			query:    "rate(http_requests_total[5m])",
+			expected: []string{"http_requests_total"},
+		},
+		{
+			name:     "nested functions",
+			query:    "sum(rate(requests[5m]))",
+			expected: []string{"requests"},
+		},
+
+		// Category 3: Binary Operations (2 tests - multiple metrics)
+		{
+			name:     "two metrics",
+			query:    "metric_a + metric_b",
+			expected: []string{"metric_a", "metric_b"},
+		},
+		{
+			name:     "three metrics nested",
+			query:    "(a + b) / c",
+			expected: []string{"a", "b", "c"},
+		},
+
+		// Category 4: Deduplication (1 test - critical behavior)
+		{
+			name:     "duplicate metric",
+			query:    "up + up",
+			expected: []string{"up"},
+		},
+
+		// Category 5: Edge Cases (2 tests - boundary behaviors)
+		{
+			name:     "no metrics (literals only)",
+			query:    "1 + 1",
+			expected: []string{},
+		},
+		{
+			name:     "built-in function without metric",
+			query:    "time()",
+			expected: []string{},
+		},
+		{
+			name:     "comparison operator",
+			query:    "a > 5",
+			expected: []string{"a"},
+		},
+
+		// Category 6: Real Dashboard Patterns (3 tests - production queries)
+		{
+			name:     "binary op with function and labels",
+			query:    `(time() - process_start_time_seconds{job="prometheus", instance=~"$node"})`,
+			expected: []string{"process_start_time_seconds"},
+		},
+		{
+			name:     "rate with regex label matcher",
+			query:    `rate(prometheus_local_storage_ingested_samples_total{instance=~"$node"}[5m])`,
+			expected: []string{"prometheus_local_storage_ingested_samples_total"},
+		},
+		{
+			name:     "metric with negation and multiple labels",
+			query:    `prometheus_target_interval_length_seconds{quantile!="0.01", quantile!="0.05", instance=~"$node"}`,
+			expected: []string{"prometheus_target_interval_length_seconds"},
+		},
+
+		// Category 7: Error Handling (2 tests - validation)
+		{
+			name:          "empty string",
+			query:         "",
+			expectError:   true,
+			errorContains: "parse",
+		},
+		{
+			name:          "malformed expression",
+			query:         "{{invalid}}",
+			expectError:   true,
+			errorContains: "parse",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := parser.ExtractMetrics(tt.query)
+
+			// Check error expectation
+			if tt.expectError {
+				require.Error(t, err, "Expected error for query: %q", tt.query)
+				if tt.errorContains != "" {
+					require.ErrorContains(t, err, tt.errorContains,
+						"Error should contain %q for query: %q", tt.errorContains, tt.query)
+				}
+				return
+			}
+
+			require.NoError(t, err, "Unexpected error for query: %q", tt.query)
+
+			// Check result matches expected (order-independent for multiple metrics)
+			require.ElementsMatch(t, tt.expected, result,
+				"ExtractMetrics(%q) returned unexpected metrics", tt.query)
+		})
+	}
+}