[processor/metricsgeneration] Generate metrics even when the second m…

…etric's value is 0 (open-telemetry#35537)

**Description:**
Originally, this processor would not generate a new metric if the value
of the metric configured as `metric2` was `0`. There are valid reasons
why this calculation should still be done, and a new metric should be
calculated.

**Link to tracking Issue:** Resolves open-telemetry#35533

**Testing:**
Added tests for each calculation type to show expected results when the
second metric's value is 0.

.chloggen/metricsgeneration_metric2_0.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: metricsgenerationprocessor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Generate metrics even when the second metric's value is 0
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35533]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

processor/metricsgenerationprocessor/processor.go

@@ -61,9 +61,6 @@ func (mgp *metricsGenerationProcessor) processMetrics(_ context.Context, md pmet
 					continue
 				}
 				operand2 = getMetricValue(metric2)
-				if operand2 <= 0 {
-					continue
-				}
 
 			} else if rule.ruleType == string(scale) {
 				operand2 = rule.scaleBy

processor/metricsgenerationprocessor/processor_test.go

@@ -391,76 +391,101 @@ func getOutputForIntGaugeTest() pmetric.Metrics {
 	return intGaugeOutputMetrics
 }
 
-func TestSumCalculateNewMetric(t *testing.T) {
-	next := new(consumertest.MetricsSink)
-	cfg := &Config{
-		Rules: []Rule{
-			{
-				Name:      "system.filesystem.capacity",
-				Unit:      "bytes",
-				Type:      "calculate",
-				Metric1:   "system.filesystem.usage",
-				Metric2:   "system.filesystem.utilization",
-				Operation: "divide",
-			},
-		},
-	}
-	factory := NewFactory()
-	mgp, err := factory.CreateMetricsProcessor(
-		context.Background(),
-		processortest.NewNopSettings(),
-		cfg,
-		next,
-	)
-	assert.NotNil(t, mgp)
-	assert.NoError(t, err)
-
-	assert.True(t, mgp.Capabilities().MutatesData)
-	require.NoError(t, mgp.Start(context.Background(), nil))
-
-	inputMetrics, err := golden.ReadMetrics(filepath.Join("testdata", "filesystem_metrics_input.yaml"))
-	assert.NoError(t, err)
-
-	err = mgp.ConsumeMetrics(context.Background(), inputMetrics)
-	assert.NoError(t, err)
-
-	got := next.AllMetrics()
-	// golden.WriteMetrics(t, filepath.Join(".", "testdata", "filesystem_metrics_expected.yaml"), got[0])
-	expected, err := golden.ReadMetrics(filepath.Join("testdata", "filesystem_metrics_expected.yaml"))
-	assert.NoError(t, err)
-	assert.Len(t, got, 1)
-	err = pmetrictest.CompareMetrics(expected, got[0],
-		pmetrictest.IgnoreMetricDataPointsOrder(),
-		pmetrictest.IgnoreStartTimestamp(),
-		pmetrictest.IgnoreTimestamp())
-	assert.NoError(t, err)
+type goldenTestCases struct {
+	name    string
+	testDir string
 }
 
-func TestResultingMetricTypes(t *testing.T) {
-	testCaseNames := []string{
-		"add_sum_sum",
-		"add_gauge_gauge",
-		"add_gauge_sum",
-		"add_sum_gauge",
-		"multiply_gauge_sum",
-		"multiply_sum_gauge",
-		"divide_gauge_sum",
-		"divide_sum_gauge",
-		"subtract_gauge_sum",
-		"subtract_sum_gauge",
-		"percent_sum_gauge",
-		"percent_gauge_sum",
+func TestGoldenFileMetrics(t *testing.T) {
+	// Test description by test data directory:
+	// input_metric_types: These tests are to ensure calculations can be done on both sums and gauges
+	// result_metric_types: These tests are to ensure the created metric's type is correct
+	// metric2_zero_value: These tests are to ensure metrics are created properly when the second metric's (metric2)
+	// value is 0.
+	testCaseNames := []goldenTestCases{
+		{
+			name:    "sum_gauge_metric",
+			testDir: "input_metric_types",
+		},
+		{
+			name:    "add_sum_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "add_gauge_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "add_gauge_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "add_sum_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "multiply_gauge_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "multiply_sum_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "divide_gauge_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "divide_sum_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "subtract_gauge_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "subtract_sum_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "percent_sum_gauge",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "percent_gauge_sum",
+			testDir: "result_metric_types",
+		},
+		{
+			name:    "metric2_zero_add",
+			testDir: "metric2_zero_value",
+		},
+		{
+			name:    "metric2_zero_subtract",
+			testDir: "metric2_zero_value",
+		},
+		{
+			name:    "metric2_zero_multiply",
+			testDir: "metric2_zero_value",
+		},
+		{
+			name:    "metric2_zero_divide",
+			testDir: "metric2_zero_value",
+		},
+		{
+			name:    "metric2_zero_percent",
+			testDir: "metric2_zero_value",
+		},
 	}
 
-	cm, err := confmaptest.LoadConf(filepath.Join("testdata", "metric_types", "gauge_sum_metrics_config.yaml"))
-	assert.NoError(t, err)
-
 	for _, testCase := range testCaseNames {
+		cm, err := confmaptest.LoadConf(filepath.Join("testdata", testCase.testDir, "config.yaml"))
+		assert.NoError(t, err)
+
 		next := new(consumertest.MetricsSink)
 		factory := NewFactory()
 		cfg := factory.CreateDefaultConfig()
 
-		sub, err := cm.Sub(fmt.Sprintf("%s/%s", "experimental_metricsgeneration", testCase))
+		sub, err := cm.Sub(fmt.Sprintf("%s/%s", "experimental_metricsgeneration", testCase.name))
 		require.NoError(t, err)
 		require.NoError(t, sub.Unmarshal(cfg))
 
@@ -476,15 +501,15 @@ func TestResultingMetricTypes(t *testing.T) {
 		assert.True(t, mgp.Capabilities().MutatesData)
 		require.NoError(t, mgp.Start(context.Background(), nil))
 
-		inputMetrics, err := golden.ReadMetrics(filepath.Join("testdata", "metric_types", "gauge_sum_metrics_input.yaml"))
+		inputMetrics, err := golden.ReadMetrics(filepath.Join("testdata", testCase.testDir, "metrics_input.yaml"))
 		assert.NoError(t, err)
 
 		err = mgp.ConsumeMetrics(context.Background(), inputMetrics)
 		assert.NoError(t, err)
 
 		got := next.AllMetrics()
-		// golden.WriteMetrics(t, filepath.Join("testdata", "metric_types", fmt.Sprintf("%s_%s", testCase, "expected.yaml")), got[0])
-		expected, err := golden.ReadMetrics(filepath.Join("testdata", "metric_types", fmt.Sprintf("%s_%s", testCase, "expected.yaml")))
+		// golden.WriteMetrics(t, filepath.Join("testdata", testCase.testDir, fmt.Sprintf("%s_%s", testCase.name, "expected.yaml")), got[0])
+		expected, err := golden.ReadMetrics(filepath.Join("testdata", testCase.testDir, fmt.Sprintf("%s_%s", testCase.name, "expected.yaml")))
 		assert.NoError(t, err)
 		assert.Len(t, got, 1)
 		err = pmetrictest.CompareMetrics(expected, got[0],

processor/metricsgenerationprocessor/testdata/input_metric_types/config.yaml

@@ -0,0 +1,8 @@
+experimental_metricsgeneration/sum_gauge_metric:
+  rules:
+    - name: system.filesystem.capacity
+      unit: bytes
+      type: calculate
+      metric1: system.filesystem.usage
+      metric2: system.filesystem.utilization
+      operation: divide

processor/metricsgenerationprocessor/testdata/metric2_zero_value/config.yaml

@@ -0,0 +1,30 @@
+experimental_metricsgeneration/metric2_zero_add:
+  rules:
+    - name: new_metric
+      metric1: capacity.total
+      metric2: capacity.used
+      operation: add
+experimental_metricsgeneration/metric2_zero_subtract:
+  rules:
+    - name: new_metric
+      metric1: capacity.total
+      metric2: capacity.used
+      operation: subtract
+experimental_metricsgeneration/metric2_zero_multiply:
+  rules:
+    - name: new_metric
+      metric1: capacity.total
+      metric2: capacity.used
+      operation: multiply
+experimental_metricsgeneration/metric2_zero_divide:
+  rules:
+    - name: new_metric
+      metric1: capacity.total
+      metric2: capacity.used
+      operation: divide
+experimental_metricsgeneration/metric2_zero_percent:
+  rules:
+    - name: new_metric
+      metric1: capacity.total
+      metric2: capacity.used
+      operation: percent

processor/metricsgenerationprocessor/testdata/metric2_zero_value/metric2_zero_add_expected.yaml

@@ -0,0 +1,31 @@
+resourceMetrics:
+  - resource: {}
+    schemaUrl: https://opentelemetry.io/schemas/1.9.0
+    scopeMetrics:
+      - metrics:
+          - description: total capacity
+            name: capacity.total
+            sum:
+              aggregationTemporality: 2
+              dataPoints:
+                - asInt: "50"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            unit: By
+          - description: used capacity
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: capacity.used
+            unit: By
+          - name: new_metric
+            sum:
+              dataPoints:
+                - asDouble: 50
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+        scope:
+          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper
+          version: latest

processor/metricsgenerationprocessor/testdata/metric2_zero_value/metric2_zero_divide_expected.yaml

@@ -0,0 +1,25 @@
+resourceMetrics:
+  - resource: {}
+    schemaUrl: https://opentelemetry.io/schemas/1.9.0
+    scopeMetrics:
+      - metrics:
+          - description: total capacity
+            name: capacity.total
+            sum:
+              aggregationTemporality: 2
+              dataPoints:
+                - asInt: "50"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            unit: By
+          - description: used capacity
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: capacity.used
+            unit: By
+        scope:
+          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper
+          version: latest

processor/metricsgenerationprocessor/testdata/metric2_zero_value/metric2_zero_multiply_expected.yaml

@@ -0,0 +1,31 @@
+resourceMetrics:
+  - resource: {}
+    schemaUrl: https://opentelemetry.io/schemas/1.9.0
+    scopeMetrics:
+      - metrics:
+          - description: total capacity
+            name: capacity.total
+            sum:
+              aggregationTemporality: 2
+              dataPoints:
+                - asInt: "50"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            unit: By
+          - description: used capacity
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: capacity.used
+            unit: By
+          - name: new_metric
+            sum:
+              dataPoints:
+                - asDouble: 0
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+        scope:
+          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper
+          version: latest

processor/metricsgenerationprocessor/testdata/metric2_zero_value/metric2_zero_percent_expected.yaml

@@ -0,0 +1,25 @@
+resourceMetrics:
+  - resource: {}
+    schemaUrl: https://opentelemetry.io/schemas/1.9.0
+    scopeMetrics:
+      - metrics:
+          - description: total capacity
+            name: capacity.total
+            sum:
+              aggregationTemporality: 2
+              dataPoints:
+                - asInt: "50"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            unit: By
+          - description: used capacity
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: capacity.used
+            unit: By
+        scope:
+          name: github.com/open-telemetry/opentelemetry-collector-contrib/receiver/hostmetricsreceiver/internal/scraper/filesystemscraper
+          version: latest