Add unit tests for bug open-telemetry#5996

sdk/trace/span_limits_test.go

@@ -183,7 +183,7 @@ func TestSpanLimits(t *testing.T) {
 		// Ensure string and string slice attributes are truncated.
 		assert.Contains(t, attrs, attribute.String("string", "ab"))
 		assert.Contains(t, attrs, attribute.StringSlice("stringSlice", []string{"ab", "de"}))
-		assert.Contains(t, attrs, attribute.String("euro", ""))
+		assert.Contains(t, attrs, attribute.String("euro", "€"))
 
 		limits.AttributeValueLengthLimit = 0
 		attrs = testSpanLimits(t, limits).Attributes()

sdk/trace/span_test.go

@@ -201,37 +201,135 @@ func TestTruncateAttr(t *testing.T) {
 			attr:  strSliceAttr,
 			want:  strSliceAttr,
 		},
+	}
+
+	for _, test := range tests {
+		name := fmt.Sprintf("%s->%s(limit:%d)", test.attr.Key, test.attr.Value.Emit(), test.limit)
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, test.want, truncateAttr(test.limit, test.attr))
+		})
+	}
+}
+
+func TestTruncate(t *testing.T) {
+	type group struct {
+		limit    int
+		input    string
+		expected string
+	}
+
+	tests := []struct {
+		name   string
+		groups []group
+	}{
+		// Edge case: limit is negative, no truncation should occur
 		{
-			// This tests the ordinary safeTruncate().
-			limit: 10,
-			attr:  attribute.String(key, "€€€€"), // 3 bytes each
-			want:  attribute.String(key, "€€€"),
+			name: "NoTruncation",
+			groups: []group{
+				{-1, "No truncation!", "No truncation!"},
+			},
 		},
+
+		// Edge case: string is already shorter than the limit, no truncation
+		// should occur
 		{
-			// This tests truncation with an invalid UTF-8 input.
-			//
-			// Note that after removing the invalid rune,
-			// the string is over length and still has to
-			// be truncated on a code point boundary.
-			limit: 10,
-			attr:  attribute.String(key, "€"[0:2]+"hello€€"), // corrupted first rune, then over limit
-			want:  attribute.String(key, "hello€"),
+			name: "ShortText",
+			groups: []group{
+				{10, "Short text", "Short text"},
+				{15, "Short text", "Short text"},
+				{100, "Short text", "Short text"},
+			},
 		},
+
+		// Edge case: truncation happens with ASCII characters only
 		{
-			// This tests the fallback to invalidTruncate()
-			// where after validation the string does not require
-			// truncation.
-			limit: 6,
-			attr:  attribute.String(key, "€"[0:2]+"hello"), // corrupted first rune, then not over limit
-			want:  attribute.String(key, "hello"),
+			name: "ASCIIOnly",
+			groups: []group{
+				{1, "Hello World!", "H"},
+				{5, "Hello World!", "Hello"},
+				{12, "Hello World!", "Hello World!"},
+			},
+		},
+
+		// Truncation including multi-byte characters (UTF-8)
+		{
+			name: "ValidUTF-8",
+			groups: []group{
+				{7, "Hello, 世界", "Hello, "},
+				{8, "Hello, 世界", "Hello, 世"},
+				{2, "こんにちは", "こん"},
+				{3, "こんにちは", "こんに"},
+				{5, "こんにちは", "こんにちは"},
+				{12, "こんにちは", "こんにちは"},
+			},
+		},
+
+		// Truncation with invalid UTF-8 characters
+		{
+			name: "InvalidUTF-8",
+			groups: []group{
+				{11, "Invalid\x80text", "Invalidtext"},
+				// Do not modify invalid text if equal to limit.
+				{11, "Valid text\x80", "Valid text\x80"},
+				// Do not modify invalid text if under limit.
+				{15, "Valid text\x80", "Valid text\x80"},
+				{5, "Hello\x80World", "Hello"},
+				{11, "Hello\x80World\x80!", "HelloWorld!"},
+				{15, "Hello\x80World\x80Test", "HelloWorldTest"},
+				{15, "Hello\x80\x80\x80World\x80Test", "HelloWorldTest"},
+				{15, "\x80\x80\x80Hello\x80\x80\x80World\x80Test\x80\x80", "HelloWorldTest"},
+			},
+		},
+
+		// Truncation with mixed validn and invalid UTF-8 characters
+		{
+			name: "MixedUTF-8",
+			groups: []group{
+				{6, "€"[0:2] + "hello€€", "hello€"},
+				{6, "€" + "€"[0:2] + "hello", "€hello"},
+				{11, "Valid text\x80📜", "Valid text📜"},
+				{11, "Valid text📜\x80", "Valid text📜"},
+				{14, "😊 Hello\x80World🌍🚀", "😊 HelloWorld🌍🚀"},
+				{14, "😊\x80 Hello\x80World🌍🚀", "😊 HelloWorld🌍🚀"},
+				{14, "😊\x80 Hello\x80World🌍\x80🚀", "😊 HelloWorld🌍🚀"},
+				{14, "😊\x80 Hello\x80World🌍\x80🚀\x80", "😊 HelloWorld🌍🚀"},
+				{14, "\x80😊\x80 Hello\x80World🌍\x80🚀\x80", "😊 HelloWorld🌍🚀"},
+			},
+		},
+
+		// Edge case: empty string, should return empty string
+		{
+			name: "Empty",
+			groups: []group{
+				{5, "", ""},
+			},
+		},
+
+		// Edge case: limit is 0, should return an empty string
+		{
+			name: "Zero",
+			groups: []group{
+				{0, "Some text", ""},
+				{0, "", ""},
+			},
 		},
 	}
 
-	for _, test := range tests {
-		name := fmt.Sprintf("%s->%s(limit:%d)", test.attr.Key, test.attr.Value.Emit(), test.limit)
-		t.Run(name, func(t *testing.T) {
-			assert.Equal(t, test.want, truncateAttr(test.limit, test.attr))
-		})
+	for _, tt := range tests {
+		for _, g := range tt.groups {
+			t.Run(tt.name, func(t *testing.T) {
+				t.Parallel()
+
+				got := safeTruncate(g.input, g.limit)
+				assert.Equalf(
+					t, g.expected, got,
+					"input: %q([]rune%v))\ngot: %q([]rune%v)\nwant %q([]rune%v)",
+					g.input, []rune(g.input),
+					got, []rune(got),
+					g.expected, []rune(g.expected),
+				)
+			})
+		}
 	}
 }