Fix floating point regex with zero exponent

src/runestone.jl

@@ -100,7 +100,7 @@ function format_float_literals(ctx::Context, node::Node)
     (?:(?:[1-9]\d*)|0)   # Non-zero followed by any digit, or just a single zero
     \.                   # Decimal point
     (?:(?:\d*[1-9])|0)   # Any digit with a final nonzero, or just a single zero
-    (?:[ef][+-]?[1-9]\d*)?
+    (?:[ef][+-]?(?:[1-9]\d*|0))?
     $
     """x
     if occursin(r, str)

test/runtests.jl

@@ -116,16 +116,15 @@ end
         ["1.0", "1.", "01.", "001.", "001.00", "1.00"] => "1.0",
         ["0.1", ".1", ".10", ".100", "00.100", "0.10"] => "0.1",
         ["1.1", "01.1", "1.10", "1.100", "001.100", "01.10"] => "1.1",
-        ["1e3", "01e3", "01.e3", "1.e3", "1.000e3", "01.00e3"] => "1.0e3",
-        ["1e+3", "01e+3", "01.e+3", "1.e+3", "1.000e+3", "01.00e+3"] => "1.0e+3",
-        ["1e-3", "01e-3", "01.e-3", "1.e-3", "1.000e-3", "01.00e-3"] => "1.0e-3",
-        ["1E3", "01E3", "01.E3", "1.E3", "1.000E3", "01.00E3"] => "1.0e3",
-        ["1E+3", "01E+3", "01.E+3", "1.E+3", "1.000E+3", "01.00E+3"] => "1.0e+3",
-        ["1E-3", "01E-3", "01.E-3", "1.E-3", "1.000E-3", "01.00E-3"] => "1.0e-3",
-        ["1f3", "01f3", "01.f3", "1.f3", "1.000f3", "01.00f3"] => "1.0f3",
-        ["1f+3", "01f+3", "01.f+3", "1.f+3", "1.000f+3", "01.00f+3"] => "1.0f+3",
-        ["1f-3", "01f-3", "01.f-3", "1.f-3", "1.000f-3", "01.00f-3"] => "1.0f-3",
     ]
+    for a in ("e", "E", "f"), b in ("", "+", "-"), c in ("3", "0", "12")
+        abc = a * b * c
+        abc′ = replace(abc, "E" => "e")
+        push!(
+            test_cases,
+            ["1$(abc)", "01$(abc)", "01.$(abc)", "1.$(abc)", "1.000$(abc)", "01.00$(abc)"] => "1.0$(abc′)",
+        )
+    end
     mod = Module()
     for prefix in ("", "-", "+")
         for (as, b) in test_cases