Made it clear that we are using SystemVerilog by renaming HDL files to end in .sv rather than .v

tests/seven_seg_tb.sv

@@ -0,0 +1,68 @@
+`include "seven_seg.v"
+
+module seven_seg_tb();
+    logic [3:0] in_num;
+    logic [0:0] in_rbi_inv;
+    logic [7:0] out_segments;
+    logic [7:0] true_segments[17];
+
+    seven_seg dut(in_num, in_rbi_inv, out_segments);
+
+    integer N;
+    integer i;
+    integer error_count;
+    initial begin
+
+        // Initialise truth table
+        true_segments[0 ] = 8'b11111101;
+        true_segments[1 ] = 8'b01100001;
+        true_segments[2 ] = 8'b11011011;
+        true_segments[3 ] = 8'b11110011;
+        true_segments[4 ] = 8'b01100111;
+        true_segments[5 ] = 8'b10110111;
+        true_segments[6 ] = 8'b10111111;
+        true_segments[7 ] = 8'b11100001;
+        true_segments[8 ] = 8'b11111111;
+        true_segments[9 ] = 8'b11100111;
+        true_segments[10] = 8'b11101111;
+        true_segments[11] = 8'b00111111;
+        true_segments[12] = 8'b10011101;
+        true_segments[13] = 8'b01111011;
+        true_segments[14] = 8'b10011111;
+        true_segments[15] = 8'b10001111;
+        true_segments[16] = 8'b00000000;
+        
+        $display("Beginning seven-segment tests");
+
+        in_num = 4'd0;
+        in_rbi_inv = 1'b0;
+        error_count = 0;
+        #1;
+        if (out_segments !== true_segments[16]) begin
+            $display("\t\x1b[38;5;9mNumber 0b%b failed to decode to 0b%b, producing 0b%b\x1b[m", in_num, true_segments[16], out_segments);
+            error_count = error_count + 1;
+        end
+        for (N=1; N < 15; ++N) begin
+            in_num = in_num + 1;
+            #1;
+            if (out_segments !== true_segments[N]) begin
+                $display("\t\x1b[38;5;9mNumber 0b%b failed to decode to 0b%b, producing 0b%b\x1b[m", in_num, true_segments[N], out_segments);
+                error_count = error_count + 1;
+            end
+        end
+
+        in_num = 4'd0;
+        in_rbi_inv = 1'b1;
+        for (N=0; N < 15; ++N) begin
+            #1;
+            if (out_segments !== true_segments[N]) begin
+                $display("\t\x1b[38;5;9mNumber 0b%b failed to decode to 0b%b, producing 0b%b\x1b[m", in_num, true_segments[N], out_segments);
+                error_count = error_count + 1;
+            end
+            in_num = in_num + 1;
+        end
+
+        if (error_count == 0) $display("\x1b[38;5;10mAll seven-segment tests passing\x1b[m");
+        else $display("\x1b[38;5;9m%0d seven-segment test(s) failing\x1b[m", error_count);
+    end
+endmodule