feat: Implement Diagnostics.BySeverity filtering (#288)

Co-authored-by: Kemal Hadimli <[email protected]>

provider/diag/diagnostics.go

@@ -152,6 +152,24 @@ func (diags Diagnostics) CountBySeverity(sev Severity, includeSquashed bool) uin
 	return count
 }
 
+// BySeverity returns a subset of diagnostics matching the given severity.
+func (diags Diagnostics) BySeverity(sevs ...Severity) Diagnostics {
+	sevMap := make(map[Severity]struct{}, len(sevs))
+	for i := range sevs {
+		sevMap[sevs[i]] = struct{}{}
+	}
+
+	ret := make(Diagnostics, 0, len(diags))
+	for _, d := range diags {
+		if _, ok := sevMap[d.Severity()]; !ok {
+			continue
+		}
+		ret = append(ret, d)
+	}
+
+	return ret
+}
+
 func (diags Diagnostics) Redacted() Diagnostics {
 	res := make(Diagnostics, len(diags))
 	for i := range diags {

provider/diag/diagnostics_test.go

@@ -3,6 +3,7 @@ package diag
 import (
 	"errors"
 	"sort"
+	"strconv"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -238,3 +239,48 @@ func TestDiagnostics_Sort(t *testing.T) {
 		}
 	}
 }
+
+func TestDiagnostics_BySeverity(t *testing.T) {
+	diagSet := Diagnostics{
+		NewBaseError(errors.New("warn test 1"), RESOLVING, WithSeverity(WARNING)),
+		NewBaseError(errors.New("err test 1"), RESOLVING),
+		NewBaseError(errors.New("ign test 1"), RESOLVING, WithSeverity(IGNORE)),
+		NewBaseError(errors.New("warn test 2"), RESOLVING, WithSeverity(WARNING)),
+		NewBaseError(errors.New("ign test 2"), RESOLVING, WithSeverity(IGNORE)),
+		NewBaseError(errors.New("err test 2"), RESOLVING),
+	}
+
+	cases := []struct {
+		sevs         []Severity
+		expectedErrs []string
+	}{
+		{
+			sevs:         []Severity{WARNING},
+			expectedErrs: []string{"warn test 1", "warn test 2"},
+		},
+		{
+			sevs:         []Severity{ERROR, WARNING},
+			expectedErrs: []string{"warn test 1", "err test 1", "warn test 2", "err test 2"},
+		},
+		{
+			sevs:         []Severity{IGNORE, PANIC},
+			expectedErrs: []string{"ign test 1", "ign test 2"},
+		},
+		{
+			sevs:         []Severity{PANIC},
+			expectedErrs: []string{},
+		},
+	}
+	for caseNo := range cases {
+		t.Run("Test #"+strconv.Itoa(caseNo+1), func(t *testing.T) {
+			tc := cases[caseNo]
+			res := diagSet.BySeverity(tc.sevs...)
+			assert.Equal(t, len(tc.expectedErrs), len(res))
+			resErrs := make([]string, len(res))
+			for i := range res {
+				resErrs[i] = res[i].Error()
+			}
+			assert.Equal(t, tc.expectedErrs, resErrs)
+		})
+	}
+}