1 files changed, 53 insertions, 0 deletions
diff --git a/src/strconv/ctoa_test.go b/src/strconv/ctoa_test.go
new file mode 100644
index 0000000..8b77898
--- /dev/null
+++ b/src/strconv/ctoa_test.go
@@ -0,0 +1,53 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	. "strconv"
+	"testing"
+)
+
+func TestFormatComplex(t *testing.T) {
+	tests := []struct {
+		c       complex128
+		fmt     byte
+		prec    int
+		bitSize int
+		out     string
+	}{
+		// a variety of signs
+		{1 + 2i, 'g', -1, 128, "(1+2i)"},
+		{3 - 4i, 'g', -1, 128, "(3-4i)"},
+		{-5 + 6i, 'g', -1, 128, "(-5+6i)"},
+		{-7 - 8i, 'g', -1, 128, "(-7-8i)"},
+
+		// test that fmt and prec are working
+		{3.14159 + 0.00123i, 'e', 3, 128, "(3.142e+00+1.230e-03i)"},
+		{3.14159 + 0.00123i, 'f', 3, 128, "(3.142+0.001i)"},
+		{3.14159 + 0.00123i, 'g', 3, 128, "(3.14+0.00123i)"},
+
+		// ensure bitSize rounding is working
+		{1.2345678901234567 + 9.876543210987654i, 'f', -1, 128, "(1.2345678901234567+9.876543210987654i)"},
+		{1.2345678901234567 + 9.876543210987654i, 'f', -1, 64, "(1.2345679+9.876543i)"},
+
+		// other cases are handled by FormatFloat tests
+	}
+	for _, test := range tests {
+		out := FormatComplex(test.c, test.fmt, test.prec, test.bitSize)
+		if out != test.out {
+			t.Fatalf("FormatComplex(%v, %q, %d, %d) = %q; want %q",
+				test.c, test.fmt, test.prec, test.bitSize, out, test.out)
+		}
+	}
+}
+
+func TestFormatComplexInvalidBitSize(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatalf("expected panic due to invalid bitSize")
+		}
+	}()
+	_ = FormatComplex(1+2i, 'g', -1, 100)
+}