Add test cases for string.format covering various edge cases (#1101)

These test cases cover formatting for negative integers for %b, %o,
and %x as well as leading and trailing zeros for %x when the
argument is a string. Furthermore it covers how NaN, +Inf, and
-Inf are printed.

The discrepancy between the fixed point formatting for %s for
lists should be fixed in a future commit.

Author: zeitgeist87

ext/strings_test.go

@@ -537,6 +537,14 @@ func TestStringFormat(t *testing.T) {
 			expectedRuntimeCost:   13,
 			expectedEstimatedCost: checker.CostEstimate{Min: 13, Max: 13},
 		},
+		{
+			name:                  "negative binary formatting clause",
+			format:                "this is -5 in binary: %b",
+			formatArgs:            "-5",
+			expectedOutput:        "this is -5 in binary: -101",
+			expectedRuntimeCost:   13,
+			expectedEstimatedCost: checker.CostEstimate{Min: 13, Max: 13},
+		},
 		{
 			name:                  "uint support for binary formatting",
 			format:                "unsigned 64 in binary: %b",
@@ -561,6 +569,14 @@ func TestStringFormat(t *testing.T) {
 			expectedRuntimeCost:   11,
 			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
 		},
+		{
+			name:                  "negative octal formatting clause",
+			format:                "%o",
+			formatArgs:            "-11",
+			expectedOutput:        "-13",
+			expectedRuntimeCost:   11,
+			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
+		},
 		{
 			name:                  "uint support for octal formatting clause",
 			format:                "this is an unsigned octal: %o",
@@ -571,9 +587,9 @@ func TestStringFormat(t *testing.T) {
 		},
 		{
 			name:                  "lowercase hexadecimal formatting clause",
-			format:                "%x is 20 in hexadecimal",
+			format:                "%x is 30 in hexadecimal",
 			formatArgs:            "30",
-			expectedOutput:        "1e is 20 in hexadecimal",
+			expectedOutput:        "1e is 30 in hexadecimal",
 			expectedRuntimeCost:   13,
 			expectedEstimatedCost: checker.CostEstimate{Min: 13, Max: 13},
 		},
@@ -585,6 +601,14 @@ func TestStringFormat(t *testing.T) {
 			expectedRuntimeCost:   13,
 			expectedEstimatedCost: checker.CostEstimate{Min: 13, Max: 13},
 		},
+		{
+			name:                  "negative hexadecimal formatting clause",
+			format:                "%x is -30 in hexadecimal",
+			formatArgs:            "-30",
+			expectedOutput:        "-1e is -30 in hexadecimal",
+			expectedRuntimeCost:   13,
+			expectedEstimatedCost: checker.CostEstimate{Min: 13, Max: 13},
+		},
 		{
 			name:                  "unsigned support for hexadecimal formatting clause",
 			format:                "%X is 6000 in hexadecimal",
@@ -617,6 +641,14 @@ func TestStringFormat(t *testing.T) {
 			expectedRuntimeCost:   11,
 			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
 		},
+		{
+			name:                  "byte support with hexadecimal formatting clause leading zero",
+			format:                "%x",
+			formatArgs:            `b"\x00\x00byte string\x00"`,
+			expectedOutput:        "00006279746520737472696e6700",
+			expectedRuntimeCost:   11,
+			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
+		},
 		{
 			name:                  "byte support with uppercase hexadecimal formatting clause",
 			format:                "%X",
@@ -661,6 +693,42 @@ func TestStringFormat(t *testing.T) {
 			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
 			locale:                "en_US",
 		},
+		{
+			name:                  "default precision for string",
+			format:                "%s",
+			formatArgs:            "2.71",
+			expectedOutput:        "2.71",
+			expectedRuntimeCost:   11,
+			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
+			locale:                "en_US",
+		},
+		{
+			name:                  "default list precision for string",
+			format:                "%s",
+			formatArgs:            "[2.71]",
+			expectedOutput:        "[2.710000]",
+			expectedRuntimeCost:   21,
+			expectedEstimatedCost: checker.CostEstimate{Min: 21, Max: 21},
+			locale:                "en_US",
+		},
+		{
+			name:                  "default scientific notation for string",
+			format:                "%s",
+			formatArgs:            "0.000000002",
+			expectedOutput:        "2e-09",
+			expectedRuntimeCost:   11,
+			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
+			locale:                "en_US",
+		},
+		{
+			name:                  "default list scientific notation for string",
+			format:                "%s",
+			formatArgs:            "[0.000000002]",
+			expectedOutput:        "[0.000000]",
+			expectedRuntimeCost:   21,
+			expectedEstimatedCost: checker.CostEstimate{Min: 21, Max: 21},
+			locale:                "en_US",
+		},
 		{
 			name:                  "unicode output for scientific notation",
 			format:                "unescaped unicode: %e, escaped unicode: %e",
@@ -697,6 +765,30 @@ func TestStringFormat(t *testing.T) {
 			expectedEstimatedCost: checker.CostEstimate{Min: 11, Max: 11},
 			locale:                "en_US",
 		},
+		{
+			name:           "NaN support for string",
+			format:         "%s",
+			formatArgs:     `double("NaN")`,
+			expectedOutput: "NaN",
+		},
+		{
+			name:           "positive infinity support for string",
+			format:         "%s",
+			formatArgs:     `double("Inf")`,
+			expectedOutput: "+Inf",
+		},
+		{
+			name:           "negative infinity support for string",
+			format:         "%s",
+			formatArgs:     `double("-Inf")`,
+			expectedOutput: "-Inf",
+		},
+		{
+			name:           "infinity list support for string",
+			format:         "%s",
+			formatArgs:     `[double("NaN"),double("+Inf"), double("-Inf")]`,
+			expectedOutput: `["NaN", "+Inf", "-Inf"]`,
+		},
 		{
 			name:                  "uint support for decimal clause",
 			format:                "%d",
@@ -753,6 +845,14 @@ func TestStringFormat(t *testing.T) {
 			expectedRuntimeCost:   12,
 			expectedEstimatedCost: checker.CostEstimate{Min: 12, Max: 12},
 		},
+		{
+			name:                  "small duration support for string",
+			format:                "%s",
+			formatArgs:            `duration("2ns")`,
+			expectedOutput:        "0.000000002s",
+			expectedRuntimeCost:   12,
+			expectedEstimatedCost: checker.CostEstimate{Min: 12, Max: 12},
+		},
 		{
 			name:                  "list support for string",
 			format:                "%s",