wip

src/ledger/file_test.go

@@ -1,6 +1,8 @@
 package ledger
 
 import (
+	"encoding/base64"
+	"fmt"
 	"os"
 	"path"
 	"path/filepath"
@@ -290,3 +292,83 @@ func TestFilesOfDir(t *testing.T) {
 		t.Error(paths)
 	}
 }
+
+func TestFilesTempGetLastNLines(t *testing.T) {
+	cases := map[string]struct {
+		input string
+		n     int
+		want  []string
+	}{
+		"empty": {},
+		"get n lines from empty file": {
+			input: "",
+			n:     5,
+			want:  []string{},
+		},
+		"get 0 lines from file": {
+			input: "#a\n#b",
+			n:     0,
+			want:  []string{},
+		},
+		"get 3 lines from 2 line file": {
+			input: "#a\n#b",
+			n:     3,
+			want:  []string{"#a", "#b"},
+		},
+		"get 2 lines from 3 line file": {
+			input: "#a\n#b\n#c",
+			n:     2,
+			want:  []string{"#b", "#c"},
+		},
+	}
+
+	for name, d := range cases {
+		c := d
+		t.Run(name, func(t *testing.T) {
+			p := path.Join(t.TempDir(), base64.URLEncoding.EncodeToString([]byte(t.Name())))
+			os.WriteFile(p, []byte(c.input), os.ModePerm)
+			files, err := NewFiles(p)
+			if err != nil {
+				panic(err)
+			}
+			if got, err := files.TempGetLastNLines(c.n); err != nil {
+				t.Fatal(err)
+			} else if fmt.Sprint(got) != fmt.Sprint(c.want) {
+				for i := range c.want {
+					t.Logf("want[%d] = %q", i, c.want[i])
+				}
+				for i := range got {
+					t.Logf(" got[%d] = %q", i, got[i])
+				}
+				t.Errorf("wanted\n\t%+v,  got\n\t%+v", c.want, got)
+			}
+		})
+	}
+}
+
+func TestFilesTempSetLastNLines(t *testing.T) {
+	cases := map[string]struct {
+		given string
+		input []string
+		n     int
+		want  string
+	}{
+		"empty": {},
+	}
+
+	for name, d := range cases {
+		c := d
+		t.Run(name, func(t *testing.T) {
+			p := path.Join(t.TempDir(), base64.URLEncoding.EncodeToString([]byte(t.Name())))
+			os.WriteFile(p, []byte(c.given), os.ModePerm)
+			files := Files([]string{p})
+			if err := files.TempSetLastNLines(c.n, c.input); err != nil {
+				t.Fatal(err)
+			}
+			got, _ := os.ReadFile(p)
+			if string(got) != c.want {
+				t.Errorf("want\n\t%s, got\n\t%s", c.want, got)
+			}
+		})
+	}
+}