db: initialize baseLevel in compaction tests

Author: RaduBerinde

compaction_picker.go

@@ -185,7 +185,8 @@ type pickedCompaction struct {
 	// levels that get compacted in multi level compactions
 	extraLevels []*compactionLevel
 	inputs      []compactionLevel
-	// LBase at the time of compaction picking.
+	// LBase at the time of compaction picking. Might be uninitialized for
+	// intra-L0 compactions.
 	baseLevel int
 	// L0-specific compaction info. Set to a non-nil value for all compactions
 	// where startLevel == 0 that were generated by L0Sublevels.
@@ -230,6 +231,9 @@ func newPickedCompaction(
 	l0Organizer *manifest.L0Organizer,
 	startLevel, outputLevel, baseLevel int,
 ) *pickedCompaction {
+	if outputLevel > 0 && baseLevel == 0 {
+		panic("base level cannot be 0")
+	}
 	if startLevel > 0 && startLevel < baseLevel {
 		panic(fmt.Sprintf("invalid compaction: start level %d should not be empty (base level %d)",
 			startLevel, baseLevel))
@@ -255,14 +259,16 @@ func newPickedCompaction(
 // determining the target output file size, overlap bytes, and expanded
 // bytes, taking into account the base level.
 func adjustedOutputLevel(outputLevel int, baseLevel int) int {
-	adjustedOutputLevel := outputLevel
-	if adjustedOutputLevel > 0 {
-		// Output level is in the range [baseLevel, numLevels]. For the purpose of
-		// determining the target output file size, overlap bytes, and expanded
-		// bytes, we want to adjust the range to [1,numLevels].
-		adjustedOutputLevel = 1 + outputLevel - baseLevel
-	}
-	return adjustedOutputLevel
+	if outputLevel == 0 {
+		return 0
+	}
+	if baseLevel == 0 {
+		panic("base level cannot be 0")
+	}
+	// Output level is in the range [baseLevel, numLevels). For the purpose of
+	// determining the target output file size, overlap bytes, and expanded
+	// bytes, we want to adjust the range to [1, numLevels).
+	return 1 + outputLevel - baseLevel
 }
 
 func newPickedCompactionFromL0(

compaction_picker_test.go

@@ -1063,8 +1063,9 @@ func TestPickedCompactionSetupInputs(t *testing.T) {
 			}
 
 			pc := &pickedCompaction{
-				cmp:    DefaultComparer.Compare,
-				inputs: []compactionLevel{{level: -1}, {level: -1}},
+				cmp:       DefaultComparer.Compare,
+				baseLevel: 1,
+				inputs:    []compactionLevel{{level: -1}, {level: -1}},
 			}
 			pc.startLevel, pc.outputLevel = &pc.inputs[0], &pc.inputs[1]
 			var currentLevel int